The Democratic Republic of Congo and defeated M23 rebels Monday failed to sign a peace deal hoped to be a key step in stabilising the conflict-prone east after Kinshasa demanded the agreement be revised.

The "DRC delegation has aborted the signing of agreement with M23," Ugandan government spokesman Ofwono Opondo said, adding that the meeting was adjourned without a new date scheduled.

The M23 rebels, one of many armed groups operating in the mineral-rich but impoverished east of the DR Congo, have been routed by the national army, who are backed by a 3,000-strong special UN intervention brigade.

But DR Congo Foreign Affairs Minister Raymond Tshibanda said Kinshasa was committed to peace.

"We have been engaged in this process for several months now... We have encountered some difficulties over issues important to us, and we think that these difficulties can be removed before finalising the process," he said.

Allegedly supported by neighbouring Rwanda and Uganda but seemingly abandoned by their sponsors due to international pressure, the M23 announced last week that their 18-month insurgency was over.

Delegations from both Kinshasa's government and the rebels arrived Monday evening at Uganda's State House in Entebbe, a town close to Kampala on the shores of Lake Victoria, where the rebels had been expected to formalise the end of their rebellion in writing.

International observers, including from the United Nations and African Union, as well as from Belgium, Britain, France and Norway, also turned up to witness the deal, Opondo said.

With Kinshasa stalling, it is not immediately certain what will happen next. But Ugandan Defence Minister and chief mediator Crispus Kiyonga said he remained optimistic.

"We have a problem on our hands in eastern DRC which everybody has agreed needs a political solution... so, I think, an agreement will be reached," Kiyonga said.

"We need time to consult with each party, we can't arbitrarily calculate the time now... there are issues of fine-tuning language and some words," he added.

The M23, a mainly ethnic Tutsi force of mutineers from the Congolese army, have no military leverage left and little room for manoeuvre.

There was no immediate reaction from the rebels.

Lack of deal a disappointment

A key outstanding issue is the fate of about 1,500 M23 fighters who have crossed into Uganda and are languishing in camps along the border. Uganda has refused to hand them over to the DR Congo.

Around 100 more injured rebels have crossed to Rwanda.

Kinshasa had said earlier the rebels would be dealt with "case by case". Many rank-and-file fighters were expected to be given the option to return to the Congolese army.

More complicated is the fate of some 100 M23 commanders. These include M23 leader Sultani Makenga, accused of participating in several massacres, mutilations, abductions and sexual violence, sometimes against children.

The failure -- for now, at least -- to sign a deal will disappoint many. The UN special envoy to the Great Lakes, Mary Robinson, told AFP that signing the accord would be "a very important step for peace".

After defeating M23, she said operations would follow to neutralise other rebel groups in a concerted effort to end one of Africa's most brutal and longest-running wars.

But even if a deal is signed, stabilising eastern DR Congo will not be easy. Previous peace deals for the region have foundered because they were not implemented or did not address underlying problems.

Oxfam on Monday warned the "conflict is far from over", noting over 30 other armed groups operate in the region and civilians risk violence on a daily basis.

Robinson said she believed Rwandan President Paul Kagame and Ugandan President Yoweri Museveni -- who deny backing the M23 -- were committed to an 11-nation regional peace agreement signed in February.

She said the priority would now shift to defeating the DR Congo-based Democratic Forces for the Liberation of Rwanda (FDLR), a descendant of Hutu extremist groups that carried out the 1994 genocide in Rwanda.

Rwanda's minority Tutsi-led government views the FDLR as a major security threat. Dealing with the group is seen as crucial to addressing the neighbouring country's concerns and preventing the emergence of yet another Rwandan-backed proxy.

burs-pjm/jmm