The Rwanda-backed M23 armed group has taken control of the mining hub of Walikale in DR Congo, local sources said Thursday, despite attempts to broker a ceasefire this week.

The seizure of the town of around 60,000 people late on Wednesday marks the farthest west the anti-government group has advanced into the interior of the Democratic Republic of Congo since it emerged in 2012.

It comes just after Congolese President Felix Tshisekedi and his Rwandan counterpart Paul Kagame held surprise talks in Doha on Tuesday, expressing their support for a ceasefire.

But the terms of any truce remain unclear, with mediator Qatar saying further negotiations were necessary.

“Walikale-centre is occupied by the M23… We retreated to avoid human losses,” an officer in the DRC’s military (FARDC) told AFP, saying its forces were now around 30 kilometres (20 miles) away in Mubi.

A separate security source confirmed the capture and also said fighting took place in Mubi on Thursday.

The offensive had already caused mining group, Alphamin, this month to evacuate its employees and halt operations at the world’s third most productive tin mine.

The Bisie site produces the tin ore cassiterite and is located in the Walikale district of North Kivu province.

The halt in mining drove up prices of tin, while concerns rise over the supply chain of the valuable metal used to solder electronic components onto printed circuit boards.

The boom in the electronics and renewable energy sectors is fuelling growing demand, according to analysts.

The region also has several gold mines.

The M23 fighters “are in the neighbourhoods of Walikale”, Fiston Misona, a civil society representative from the community, said early Thursday.

Another resident, who spoke on condition of anonymity, said they saw groups of armed fighters “through the windows” of their house.

A Doctors Without Borders (MSF) base was “caught in the crossfire” during the fighting but no injuries were reported, local official Marco Doneda said.