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.

The M23 militia, funded and directed by Rwanda, said it took the city of Goma, terrifying its people, many of whom sought shelter there after fleeing the rebel advance.

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.

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.

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.

Rwandan backed rebels have entered the city of Goma, a key city in neighboring Democratic Republic of Congo. Could the mineral rich region be in danger of tipping into all out regional conflict?

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,

Fighting has escalated sharply in recent weeks in eastern Congo, where rebels have seized key towns and are closing in on the city of Goma, the government’s last stronghold in the North Kivu province,

Congo has severed diplomatic ties with Rwanda as fighting between Rwanda-backed rebels and government forces rages around the key eastern city of Goma, leaving at least 13 peacekeepers and foreign soldiers dead and displacing thousands of civilians.

M23 insurgency has intensified, with the Rwanda-backed rebels seizing control of more territory than ever before, prompting the U.N. to warn of the risk of a broader war. South Africa said nine of its peacekeepers were killed in fighting.