The better-prepared Congolese troops, the backing of UN forces and no reaction from Rwanda have left the M23 rebel movement in eastern DR Congo in its death throes, experts say.

The beleaguered M23 leader, Bertrand Bisimwa, called at the weekend for a ceasefire, after government troops succeeded in forcing the M23 from their final stronghold in the country's troubled North Kivu province.

But pockets of M23 resistance remain and some observers warn that though the rebels have been outsmarted, the Democratic Republic of Congo's problems in the restive east are far from over.

The M23 movement was founded by ethnic Tutsi former rebels who were incorporated into the Congolese army under a 2009 peace deal but mutinied in April 2012, claiming that the pact had never been fully implemented.

After briefly seizing the regional capital and mining hub of Goma last November, the M23 entered into fresh peace talks which fell apart last month, leading the Congolese army to go on the attack in a bid to end the rebellion.

The United Nations regularly accuses neighbouring Rwanda and Uganda of covertly supporting the rebels, a claim they virulently deny.

In fact, Rwanda's inaction at times of high tension between Congolese forces and the rebels has been key to the movement's near-demise, high-ranking officials say.

"There was huge American pressure on (Rwandan President Paul) Kagame, to request him not to act," a Kinshasa-based diplomat said.

And a US State Department official told AFP that Secretary of State John Kerry had taken an active role as a go-between in Kinshasa and Kigali.

"Secretary Kerry and other officials have regularly raised our concerns about support for armed groups such as M23 with various leaders in the region including President Kagame," the official said.

This diplomatic pressure had paid off, "at least temporarily," Thierry Vircoulon of the International Crisis Group said in an interview with AFP in Nairobi.

"It worked... against the determination of Kigali, who finally abandoned the M23," he said.

The Ugandans were also "warned" and "reinforced their border controls so that the rebels didn't pass" over the frontier, a military expert in Kinshasa added.

'Hard lessons learnt'

Vircoulon believes that the government offensive against the M23 had been successful in part due to the role of the United Nations mission, known by its acronym MONUSCO, in the country.

"The support of MONUSCO, a reduction in corruption in the units concerned, a change of command and close co-ordination with the UN mission in terms of planning operations," had all helped, he said.

And a certain "unity" was established by the arrival of the UN mission's new chief, Martin Kobler, in August, replacing the "lack of understanding and mistrust" that had led to Goma's occupation last year, another military expert with knowledge of the UN mission said.

UN troops have not directly participated in the fighting that saw the government troops regain rebel-held territory, but has deployed patrols in recently liberated areas to protect civilians, allowing the army to assure those left behind of their safety.

Simple gestures such as giving rations to soldiers when they were on duty "because they know they won't be going to bed hungry," had been effective, the expert on the UN mission added.

Meanwhile, the Kinshasa-based military expert said the victories were also down to the fact the army had finally learnt "some hard lessons".

More than a hundred incompetent or idle officers had been relieved of duty, communication had been improved, soldiers were properly paid and food supplies were being distributed more effectively.

And the best-trained units, schooled by the Belgians, South Africans and Chinese, were sent to the front line, which "changed everything", the specialist said.

What follows this breakthrough is the government's responsibility, namely to keep the promises it made in February when 11 African countries signed a treaty that compelled DR Congo to promote democracy and disarm all militia, especially those threatening violence against Tutsis.

"The authorities in Kinshasa now find themselves in a position of strength," Vircoulon said.

The only problem was, he asked, "Are they going to make good use of it?"