Experts hope any chemical pollution from the incident can be "quickly contained and pollution minimised" before it affects wildlife in the region.

Dr Tom Webb, senior lecturer in marine ecology and conservation at the University of Sheffield, said: "The wildlife of the Yorkshire coast and Humber Estuary is of immense biological, cultural and economic importance.

"In addition to the wealth of marine life that is present all year round, this time of the year is crucial for many migratory species.

"Wading birds and waterfowl gather in large numbers as they move between wintering and breeding grounds, while soon Yorkshire's iconic seabirds will be coming inshore to breed at sites like the world famous Brampton Cliffs.

"Chemical pollution resulting from incidents of this kind can directly impact birds, and it can also have long-lasting effects on the marine food webs that support them.

"We have to hope that any spills can be quickly contained and pollution minimised."

A wildlife charity is "very concerned" about a "toxic mix" of jet fuel, sodium cyanide and burning plastic from the ship collision, its boss has said.

"This part of East Yorkshire has a number of really important bird reserves. Yorkshire Wildlife Trust, ourselves we have a national nature reserve [there]," Martin Slater, director of operations at Yorkshire Wildlife Trust, told presenter Mark Austin.

"There's migrating birds, there's overwintering birds - there's 150,000 overwintering birds in the Humber Estuary at the moment. There's colonies of grey seals. And the time of year for breeding birds and seal pups - it couldn't be a worse time really."

He said in the plume of black smoke there was "cyanide, fuel, plastics burning, that will eventually hit the sea surface or land further down the coast - and that's toxic to all marine life."

He added: "Our ecosystems and nature are already under threat and this kind of thing can be really catastrophic for wildlife."

Asked what the charity was ready to do, he explained: "Just to observe to see if any of those chemicals, oil or plastics come ashore. We can remove that with the help of the authorities.

"We've got over 800 volunteers we can muster along the coast in the event that we get oiled birds, so we can help to clean that up.

In the longer term though,  the Wildlife Trust and other organisations we can help to restore any damaged habitats and impacts on the precious wildlife."

Port authorities have ordered ships not to leave docks and ports along the coast of Lincolnshire and East Yorkshire, our correspondent Tom Parmenter reports.

You can watch his report here: 

It looks like we have an update on the number of people involved in the collision.

Earlier, local Tory MP Graham Stuart said one person was in hospital, but the remaining 36 mariners had been rescued.

But now East Midlands Ambulance Service has said 36 people were assessed at the scene and did not need to be transported to hospital.

Alastair Smith, head of operations for Lincolnshire at East Midlands Ambulance Service, said: "We received a call at 11.28am on Monday 10 March to North Quay in Grimsby, relating to reports of a collision between a tanker and cargo vessel off the coast of East Yorkshire.

"A total of 36 patients were assessed on scene by our ambulance crews and none required transporting to hospital."

There is a concern heavier ship fuel was spilled by the collision between the oil tanker Stena Immaculate and the container ship Solong, an expert has warned.

Dr Mark Hartl, a marine ecotoxicologist from the Centre for Marine Biodiversity & Biotechnology at Heriot-Watt University, said it may be better for the environment that the oil tanker was carrying jet fuel rather than crude oil.

He said: "Whilst the images look worrying, from the perspective of the impact to the aquatic environment it's less of a concern than if this had been crude oil because most of the jet fuel will evaporate very quickly.

"Also, the fact that it happened out at sea and not closer to land or within an estuary setting is fortuitous and will minimize the environmental impact.

"However, it will have an acute effect on organisms in the immediate aftermath of the spill and lead to various degrees of stress in exposed animals."

He added: "There must also be a concern that heavier ship fuel was spilled as a consequence of the collision which could have a more lasting effect on the coastline."

By Victoria Seabrook, climate reporter

The crash involving a cargo ship and oil tanker off the East Yorkshire coast is bad news for the sea, fish and air in the area. What we don't know yet is quite how bad it will be.

That depends on a few things - but the speed of the collision, clouds of filthy black smoke from the fires and the leaked fuel are certainly worrying.

Firstly, it matters what was on board those two massive vessels.

Analytics firm Vortexa estimates the 183m-long tanker was carrying about 130,000 barrels of jet fuel (kerosene), which is now leaking into the sea.

Jet fuel is not as sticky or viscous as heavier types of oil, thankfully, so it's less likely to clog the feathers and fur of birds and seals. It can also be broken down by natural bacteria.

But it can still poison fish and kill animals and plants on the shoreline if it makes its way into the soil there.

The Marine Conservation Society has pointed out the site in the Humber estuary is close to some protected areas and is important for seabirds and harbour porpoises.

And both ships will have been powered by a dirtier, heavier kind of oil - likely marine gas oil or heavy fuel oil, though we don't know the details yet.

Heavy fuel oil is nasty stuff.

Cheap, thick and tar-like, it can smother animals and is very dangerous if they consume it, and is extremely difficult to clean up. Let's hope this isn't creeping around the North Sea already.

We don't know how much of either the jet fuel or the oil powering the ships has leaked, or how much will be burned off in the violent fires - which themselves are ploughing black smoke and filthy air pollution into the surrounding atmosphere.

And we don't know for sure what was on the Solong cargo ship and if, or what, will go into the sea.

Cargo ship 'had sodium cyanide containers'

According to a report from maritime data provider Lloyd's List Intelligence, the ship was carrying 15 containers of sodium cyanide among other cargo.

The container vessel was also transporting an unknown quantity of alcohol, said the casualty report - an assessment of incidents at sea - citing a message from the local coastguard.

Plastic takes hundreds of years to break down, and potentially can choke or trap animals.

Many of us have seen that uncomfortable viral video of a turtle having a straw yanked out of its nose. Previous accidents on cargo ships have seen plastic Lego pieces wash up in Cornwall 25 years later.

Secondly, the impact depends on the sea and weather conditions around it.

Things like the wind and currents affect how an oil spill spreads in the sea. Scientists can draw up computer models to simulate how the oil could behave.

Thirdly, it matters how quickly this is all tackled and then cleaned up, if necessary, and if it can be.

Usually, the slower the response, the worse the impact.

The coastguard has said the incident "remains ongoing" and it has started assessing the "likely counter pollution response" that will be required.

Such a response might need the help of numerous public bodies: the government environment department, the transport department, the Environment Agency and the Maritime and Coastguard Agency.

So for now the best we can hope for - aside from the welfare of the people involved - is that not all the oil is spilled or burnt, that conditions are calm and that rescuers and those cleaning up can work swiftly.

The Solong cargo ship was carrying 15 containers of the highly toxic compound sodium cyanide, a Lloyd's List Intelligence casualty report said, according to Reuters.

Sodium cyanide releases hydrogen cyanide gas, which interferes with the body's ability to use oxygen, according to the US Centers for Disease Control and Prevention.

"Exposure to sodium cyanide can be rapidly fatal," it warns.

It is "water-reactive" and the CDC said "containers may explode when heated or if they are contaminated with water".

Sodium cyanide is used for fumigation, electroplating, extracting gold and silver from ores and chemical manufacturing.

Lloyd’s List Intelligence said the container vessel was also transporting an unknown quantity of alcohol.

Search and rescue efforts are first and foremost concerned with bringing all people who were on board the vessels to safety.

But there are also concerns over any potential oil spill - and the impact this could have on the environment.

With the collision occurring just this morning, it's too early to tell what kind of damage we could be looking at, Greenpeace has said.

In a statement, the environmentalist group said they are "monitoring" the reports "very closely".

"Both the high speed of the collision and the footage of the aftermath are cause for great concern," it added.

"Right now, our thoughts are with all those affected by the incident and the emergency services responding to the situation."

At this point, however, it's "too early to assess the extent of any environmental damage".

'Response will be crucial'

"The magnitude of any impact will depend on a number of factors, including the amount and type of oil carried by the tanker, the fuel carried by both ships, and how much of that, if any, has entered the water," it continued, speaking before it was confirmed jet fuel was spilled into the sea.

"Sea and weather conditions will also be important in determining how any spill behaves.

"In the case of an oil spill or any loss of hazardous cargo from the container ship involved, the speed of the response will also be crucial in limiting any impact."

The Stena Immaculate tanker was on a short-term charter to the US Navy's Military Sealift Command when it was struck, a US military spokesperson has said.

Earlier, we reported the tanker was part of a programme to have 10 ships capable of transporting oil for the US Army "in times of need" (see 13.47pm post).

It comes as two maritime security sources told Reuters there was no indication of any malicious activity or other actors involved in the crash.

Details of the cause of the collision are "still becoming clear", Downing Street has said.

The prime minister's official spokesman said it was an "extremely concerning situation".

He said: "We thank the emergency services for their rapid response. I understand the Department for Transport is working closely with the coastguard to help support the response to the incident.

"We're obviously monitoring the situation, we'll continue to co-ordinate the response and we're grateful to emergency personnel for their continued efforts."

Asked if there were any theories about what happened, the spokesman said: "My understanding is the details are still becoming clear, so I don't want to speculate on that."

The Marine Accident Investigation Branch has deployed a team to conduct a preliminary assessment, the spokesman added.