It is still not clear what killed fish along a stretch of canal, despite investigations.

The public alerted the Wilts and Berks Canal Trust to the "hundreds" of dead fish in a section of the waterway in Swindon last week.

The Environment Agency took samples but said there was no sign of low oxygen or pollution, so whatever caused the incident has passed.

Chris Barry, vice chair of the Swindon branch of the Wilts and Berks Canal Trust, said: "We've been going up and down here for 10 years and this is the first year we've seen it."

"Last year was a very dry year and in a different part of our canal, at Royal Wootton Bassett, there were dead fish" added Mr Barry, who said the dead fish numbered in the hundreds.

Another member of the trust, Brian Sharp, said local residents had been reporting the issue to the council and Thames Water, as well as the canal trust and the Environment Agency.

Thames Water has also been seen taking samples.

Mr Sharp said he saw "five or six times" the amount a few days before.