Eight African leaders will on Monday launch a new bid to calm eastern Democratic Republic of Congo, where the UN wants to send an 'intervention brigade' and surveillance drones to counter armed rebels.

An uprising by the M23 group, which took a large chunk of territory in November, forced the United Nations to broker its latest attempt to end more than a decade of strife.

The presidents of DR Congo, Rwanda, Burundi, Uganda, Angola, Republic of Congo, South Africa and Tanzania will sign a commitment to end the conflict on the sidelines of an African Union summit in Addis Ababa, UN officials said.

Alongside the diplomacy, the United Nations wants to toughen its mission in DR Congo with a 2,500-strong "intervention brigade" to tackle M23 and other armed groups.

Tanzania and South Africa are leading contenders to provide the first special force, UN diplomats said.

"It's not simple peacekeeping, this is peace enforcement. It is much more robust and needs the right combination of troops," said a UN peacekeeping official.

The three battalions will "neutralize the threat of the armed groups through targeted operations against command and control structures, against specific sites," said the official, speaking on condition of anonymity because UN leader Ban Ki-moon has not yet officially announced the force.

Ban has been working on new security plan to present to the UN Security Council since the M23 took the city of Goma in November, sweeping aside the DR Congo army.

UN experts have accused neighbouring Rwanda and Uganda of aiding M23. Both deny any role. But the "intervention brigade" will be charged with tackling all armed groups who have terrorised the resource-rich region over the past 15 years.

The UN Security Council has also authorized the use of surveillance drones to monitor DR Congo's border with Rwanda and UN officials hope the troops and new spies in the sky will be operating within three months.

The peacekeeping mission in DR Congo, MONUSCO, is the UN biggest peacekeeping force. It currently has about 17,000 troops and under its Security Council mandate is allowed to have up to 19,800 troops.

UN officials are still working on a final version of the political accord but are confident it will be signed in Addis Ababa on Monday.

The tougher UN force is "part of the overall package that the secretary general is presenting to the region in addition to the political framework that we believe is the key to dealing with this issue," said a second UN official.

"The leaders of the region have agreed to work together and to address the underlying issues -- economic, military, political -- and to have that binding on them."

A series of regional peace accords have been signed and collapsed since the late 1990s. But the UN hopes this will be more successful as it aims to hold the leaders "accountable", said the official.

The accord will set benchmarks for individual countries to help end the violence and these will be monitored. Under the accord the eight presidents will meet twice a year to discuss efforts to bring peace to DR Congo, the political official.

Under the deal, Ban will also name a "high profile" special envoy to the Great Lakes region.

While a ceasefire barely holds in the region, the M23 and President Joseph Kabila's government this month agreed an agenda for peace talks.

"One peace initiative after another over the last dozen years has failed to address the root causes of the Congolese war," said John Prendergast, a former advisor to the US government on Africa and co-founder of the Enough Project to combat genocide.

"Short-term security deals simply shore up Kabila's eroding power and remove international pressure" from Rwandan and Ugandan leaders Paul Kagame and Yoweri Museveni over their helping for M23, he added.

A UN envoy could work with the African Union to bring together the rival groups and government and "deal with the primary drivers of violence, including the economic roots of war and neighboring governments' role in massive smuggling networks of Congo's natural resources.

"If the economic and accountability dimensions are addressed, Congo has a chance," Prendergast said.