Congo M23 rebels will no longer join peace talks in Angola on Tuesday

Earlier on Monday, the group said it would be sending a delegation to Angola's capital Luanda on Tuesday, one day after Congo confirmed its participation, reversing the government's long-standing vow not to negotiate with the rebels.

The rebels have launched a major offensive in the east of the Congo, gaining ground this year they had never controlled before, including east Congo's two biggest cities and a host of smaller localities.

The M23 backtracked on peace talks after the European Union announced sanctions related to the offensive which targeted its political leader Bertrand Bisimwa and Rwandan army commanders among others. Rwanda denies backing the Tutsi-led rebel group.

"Successive sanctions imposed on our members, including those enacted on the eve of the Luanda discussions, severely undermine direct dialogue and make any progress impossible," a rebel alliance that includes M23 said in a statement.

Congo's presidency spokesperson Tina Salama said after the M23's announcement that Congo would still be sending a delegation to Luanda as planned.

"We confirm our participation," she said via WhatsApp message. "The delegation should normally be leaving this evening."

Angola has been trying to mediate a lasting ceasefire and lower tensions between Congo and neighbouring Rwanda.