Goma - Nearly 300 Congolese policemen arrived in the strategic rebel-held city of Goma on Friday ahead of an expected pullout by the insurgents, with the army vowing to enter the city the next day.

The M23 rebels, army mutineers who sparked international anger when they seized Goma last week in a lightning advance, have said they will withdraw 20 kilometres from the city, the main town in the Democratic Republic of Congo's mineral-rich east.

An AFP reporter saw more than 270 policemen out of an expected 450 land at Goma's port, having crossed Lake Kivu from government-controlled Bukavu some 100 kilometres south.

The policemen were due “to secure the city of Goma after the pullout of M23 rebels,” said Mondje Nounoubai, a spokesman for the United Nations peacekeeping force in the country.

DR Congo's army, which fled in disarray when the rebels seized Goma and surrounding settlements in the chronically volatile region, will enter the city on Saturday, said army chief General Francois Olenga.

“We will deploy our units tomorrow,” Olenga told AFP. “A battalion will be posted in the city and a company will be posted at the airport.”

The rebels' campaign has raised fears of a humanitarian catastrophe and wider conflict erupting from DR Congo's east, the cradle of back-to-back wars that shook the country and drew in much of the region from 1996 to 2003.

Under a pullout deal struck this week in Uganda with army chiefs from the 11-nation International Conference on the Great Lakes Region (ICGLR), senior officers from the regional bloc are travelling to Goma to monitor the withdrawal.

The M23 will leave a company of 100 fighters at the airport, and neighbouring Tanzania is also expected to send a company of soldiers to the airport under the ICGLR deal.

As the police disembarked, Ugandan Brigadier Jeffrey Muheesi said: “We are going to see the deployment of these police, we are going to discuss with the commander of M23 to remove his men, and then they take over their posts.”

The rebels, who entered Goma 10 days ago, initially agreed to leave on Thursday. Any withdrawal now would likely continue well into Saturday.

Residents have reported seeing dozens of rebel trucks carrying food and ammunition trundling through the lush green and rolling hills on the shores of Lake Kivu toward Goma, pulling back past the wreckage of last week's fighting.

However, there are still no clear signs of a large-scale pullout by the rebels, according to AFP reporters both in Goma and further toward frontline positions, including the town of Sake some 30 kilometres to the west.

M23 commander Sultani Makenga reportedly commands some 1 500 fighters, according to a Western military source, but has beefed up his force with heavy weapons and ammunition seized from fleeing government forces.

Makenga was hit with UN and United States sanctions last month over alleged killings, rapes and abductions committed by his men.

Decades of conflicts between multiple militia forces - as well as meddling by regional armies - have ravaged DR Congo's east, which holds vast mineral wealth including copper, diamonds, gold and key mobile phone component coltan.

UN experts have accused Rwanda and Uganda - which played active roles in DR Congo's 1996-2003 wars - of supporting the M23, a charge both countries deny.

Civilians, many of whom have had to flee repeated rounds of fighting over several years, are suffering.

Aid agencies are struggling to cope with the newly displaced, with some 285 000 people having fled their homes since the rebels began their uprising in April.

Tensions too are high at how the potential arrival of the army and withdrawal of the rebels will play out, with residents fearful of new rounds of looting and reprisal attacks by the army. Locals have told AFP both the M23 and the army are guilty of abuses.

The instability in DR Congo's east was exacerbated by the aftermath of the 1999 genocide in Rwanda, when Hutus implicated in the killing of some 800 000 mostly Tutsi victims fled across the Congolese border after Tutsi leader Paul Kagame came to power.

The M23 was founded by former fighters in a Tutsi rebel group whose members were integrated into the regular army under a 2009 peace deal they claim was never fully implemented.