A Congolese army tank moves into position against M23 rebels near the Rumangabo military base in Runyoni, 58km north of Goma. File photo: Reuters

Kinshasa - Rebels in the Democratic Republic of Congo's powder-keg east have surrendered after a crushing UN-backed offensive ended their 18-month insurgency in a region that has seen some of Africa's deadliest conflicts.

Kinshasa, emboldened by its biggest military victory in half a century, said its forces would keep up the momentum to go after Rwandan Hutu militia also active in the region.

The M23 rebel movement's statement on Tuesday that it would “end its rebellion” and instead pursue its goals “through purely political means” came after around 200 holdout rebels were routed from their hilltop positions overnight.

“It's a total victory for the DRC,” said government spokesman Lambert Mende, adding that the routed rebels had fled to neighbouring Rwanda. A local official said the M23's top commander Sultani Makenga was among them.

The United States hailed the rebels' surrender and urged “reaching a negotiated end to the rebellion as a critical first step to ending the instability in DRC”, said deputy State Department spokeswoman Marie Harf.

The army launched a major offensive on October 25, steadily claiming the main rebel-held towns until diehard M23 fighters were forced to hole up on three hills about 80km north of the regional capital Goma and near the Rwandan border.

The insurgents - who at their strongest occupied Goma for 10 days a year ago - called for a truce on Sunday, but the army pressed on with its assault.

The UN special force in the region - which had so far been assisting with aerial reconnaissance, intelligence and planning - joined direct combat late on Monday after getting the green light to bombard the hilltops.

“With all that the M23 left (in weapons and material), they can no longer come back,” Congolese general Jean-Lucien Bahuma, standing at the bottom of the captured hill in Chanzu, told AFP.

At its summit, Brazilian general Carlos Alberto dos Santos Cruz, commander of the UN force, congratulated the Congolese army.

“I think that it's one very important moment to the Congolese armed forces and to the Congolese people, to bring peace to this region, to have control again on this part of the territory,” he told AFP.

In Bunagana, which had been the M23's base, Aline, a clothes seller who had just returned from across the border in Uganda said she was happy. “The rebels have gone for good. They'll never come back.”

One resident returning to Goma was more restrained, warning the rebels could return “because we don't know where they've gone”.

UN experts and Kinshasa have repeatedly described the M23 as a Rwandan puppet, accusing the government in the capital Kigali of arming the group and even of sending some of its own troops to the battlefield - which the government denied.

The rebels' crushing defeat appeared to signal that the Rwandan government had finally yielded to intense diplomatic pressure and chosen to forsake its one-time proxy.

A top Rwandan official told AFP in Kigali on Tuesday that about 15 wounded M23 fighters “arrived in Rwanda on October 28”, but that was all and that the fighting had not crossed into Rwanda.

Meanwhile, Congolese government spokesman Mende said the M23 had been “top of the list” of multiple armed groups targeted for eradication in the east, and that the Rwandan Hutus were next.

“There is no more place in our country for any irregular group,” Mende said.

Now the army will “get on with disarming” the Democratic Forces for the Liberation of Rwanda (FDLR), a Kivu-based Rwandan group that includes the remnants of Hutu militia who carried out the 1994 genocide, he said.

The disbanding of the M23 marks the clearest and most significant military victory for the Congolese government since the 1963 crushing of a separatist rebellion in the southern province of Katanga.

Analysts say better preparation by the Congolese troops and the unprecedented offensive mandate granted to the special UN brigade tipped the military balance.

The heavily armed 3 000-strong UN intervention brigade joined 17 000 peacekeepers already deployed with a mission to stamp out rebel groups accused of human rights abuses including rape, murder and recruiting child soldiers.

The M23 was launched in April 2012 by ex-rebels who had been integrated into the regular army after an earlier peace deal but mutinied again, claiming that Kinshasa was failing to keep its side of the bargain.

The UN refugee agency said on Tuesday that the recent fighting had forced 10 000 civilians to flee across the border to Uganda, Rwanda's neighbour to the north.

The area of North and South Kivu has a bloody history. It saw the birth of the 1996 Rwandan-backed rebellion that toppled Mobutu Sese Seko and installed Laurent-Desire Kabila, the father of the current president.

The region was also the detonator of the 1998-2003 conflict known as the Great African War, which involved nine countries and is described as the continent's deadliest war of the modern era. - AFP