GOMA, Democratic Republic of Congo (Reuters) -Congolese M23 rebels entered the centre of the eastern city of Goma on Monday, two witnesses said, hours after they claimed to have seized the city despite the United Nations Security Council demanding an end to the offensive.

Congo has severed diplomatic ties with Rwanda as fighting between Rwanda-backed rebels and government forces rages around the key eastern city of Goma.

Tens of thousands of people are fleeing towns in the Democratic Republic of Congo's east, as rebel forces close in on the city of Goma. Explosions and gunshots were heard in city - home to more than a million people - late on Sunday evening, according to local media reports.