Rebels in the Democratic Republic of Congo hit out Monday at a move by the United Nations to deploy a peacekeeping brigade to the country's restive east, saying it was instead choosing to "make war".

"This is the war option that the United Nations is exercising," said the political leader and spokesman of the M23 rebel movement, Bertrand Bisimwa.

The United Nations has chosen "to make war against one of its partners for peace", he said, instead of "encouraging a political solution" through talks in the Ugandan capital Kampala between the rebels and DR Congo's government.

On Thursday, the UN Security Council unanimously approved the creation of a brigade of more than 2,500 troops to curb violent unrest in the resource-rich eastern provinces of North and South Kivu.

The resolution's mandate to conduct "targeted offensive operations" has never been given to a peacekeeping mission before, diplomats said.

The force is to put an end to unrest in the region, which has been gripped by conflict between armed groups for more than two decades.

A statement from Kinshasha in response to M23's comments Monday said the rebels should quit, as they "go from one failure to the next".

"Now it's more failure, tomorrow it will be bullets from the brigade. There is still time for our M23 brothers to disband," government spokesman Lambert Mende told a press conference.

The new brigade, which will support the UN mission MONUSCO already present in the country, is set to be deployed by the end of this month, DR Congo's Foreign Affairs Minister Raymond Tshibanda announced Monday.

"It has been arranged with the UN Secretary General's office that the deployment will take place 30 days after the adoption of the resolution. That means that by the end of April elements of the brigade will be in Goma and North Kivu," he said.

He said he had been given guarantees that an April 30 deadline would be respected.

Tshiband said that the first South African troops to form the brigade had already been transferred from MONUSCO and were already in place.

They will be joined by troops from Tanzania and Malawi.

DR Congo's army has been battling the M23 rebels since May last year, with the United Nations accusing Rwanda and Uganda of funding them -- accusations both countries have denied.

Fighting spiked last month after the M23 split into two factions, sending hundreds of fighters fleeing across the border into Rwanda.

They included Bosco Ntaganda, the warlord believed to be the instigator of the M23 rebellion and responsible for a string of atrocities, who is awaiting extradition to appear before the International Criminal Court after handing himself in to Rwandan authorities.

Clashes between another tribal militia, the Mai Mai, and the army in DR Congo's mining capital Lubumbashi on March 23 killed at least 23 people and injured several, spokesman Mende confirmed Monday.

The peace brigade is part of a new UN campaign to bring peace to DR Congo that includes an accord signed in February by 11 African nations pledging not to interfere in the affairs of their neighbours.