Gunfire rang out early on Monday across parts of Goma, the largest city in eastern Congo, hours after Rwanda-backed rebels said they had seized the city despite the United Nations Security Council's calling for an end to the offensive.

Congolese rebels and allied Rwandan forces entered the outskirts of Goma on Sunday and the airport in the key eastern city was no longer in use, the top UN official in the country said. Thousands fled the fighting that also killed at least 13 peacekeepers.

The Democratic Republic of Congo (DRC) has severed diplomatic ties with Rwanda, accusing it of fuelling the rebellion. At least 13 soldiers serving with peacekeeping forces in the DRC have been killed in clashes with M23 rebels,