Government soldiers in the Democratic Republic Congo are fleeing Goma in large numbers as fighters belonging to the rebel M23 group advance to the gates of the regional capital after fresh fighting erupted in the area last week, according to a UN source.
Goma airport has been closed, a Western military source said on Sunday, and hundreds of people have fled Goma, seeking refuge in nearby camps amid the most serious fighting in the area since July.
Fighting erupted in eastern DRC in April following a mutiny by former soldiers who formed the M23.
Al Jazeera's Nazanine Moshiri, reporting from Nairobi in Kenya, said: "The rebels are about 3km away from Goma, and only two from Goma's airport. They have been advancing steadily in the last 24 hours.
"Government officials and Congolese soldiers have been retreating. ... UN staff have been asked to stay indoors, international NGO workers and diplomats have been moved across the border to Rwanda.
"Goma feels like a ghost town right now."
Lieutenant-Colonel Vianney Kazarama, and M23 spokesperson, told AFP news agency that the fighters had reached Kibati, which is 5km from Goma.
"We're at the gates ... We are not in the city of Goma. It's not our ambition to take Goma. Nevertheless if [President Joseph] Kabila's army attacks us, we will pursue the enemy until it is repelled very far from Goma," he said.
There was no immediate comment on the rebel claim from the army.
UN attack helicopters launched sorties against rebels on Saturday as the UN Security Council demanded an end to foreign support for the M23, whose leader was hit by UN and US sanctions last week.
The M23, in turn, has warned UN peacekeepers that "we will respond" if they fail to stop backing the regular army by strafing rebel positions.
"Despite the UN air strikes, the rebels have an advantage. They have night vision equipment and mortars as well. People are expecting the rebel group to make some kind of advance," our correspondent reported.
"The UN is attacking the rebels from the air with attack helicopters, but so far they have not engaged with them on the ground."
In New York on Saturday, the 15-nation Security Council went into an emergency session on the crisis.
Ban Ki-moon, UN secretary-general, appealed to Rwandan President Paul Kagame to "use his influence on M23", according to Herve Ladsous, UN peacekeeping chief.
Rwanda has denied a report by UN experts that it has backed the rebels.
DRC has again accused its neighbour Rwanda of backing the M23.
Ladsous said the UN could not confirm whether Rwanda is helping the new rebel offensive but suggested that M23 "attacking forces are well-equipped and very well-supplied".
New sanctions pledged
A Security Council statement demanded an end to the M23 advance and "that any and all outside support and supply of equipment to the M23 cease immediately".
It pledged new sanctions against M23 leaders and those who help it breach UN sanctions and an arms embargo.
Last week both the UN and the US announced sanctions on Sultani Makenga, an M23 leader who is accused of masterminding killings, sex attacks, abductions and recruiting child soldiers.
While each side blames the other for the latest violence, the UN mission in DC Congo MONUSCO said the M23 had launched an offensive with heavy weapons early on Saturday, prompting the UN peacekeepers to deploy to protect civilians.
"As part of this, 10 missions were carried out by [MONUSCO] attack helicopters," it said in a statement.
"MONUSCO firmly condemns the renewal of hostilities. It calls on the M23 to immediately halt its attacks, which have caused a deterioration of the already fragile security and humanitarian situation."
Kazarama, the rebel spokesman, said MONUSCO "must stop" attacking areas under rebel control and show its neutrality.
"If they continue to strafe us, we will respond," he said.