Regional African leaders signed a deal to try to bring peace to the war-torn east of the Democratic Republic of Congo, with plans to reinforce a UN-led mission to combat rebels after years of unrest.
But with the ink still wet, the UN Security Council expressed concern at the deepening unrest in the region, once again condemning the mainly Tutsi M23 rebels, who UN investigators say are backed by Rwanda and Uganda.
Eleven countries in the Great Lakes region -- including those accused of backing rebel groups -- signed the accord at a ceremony in the Ethiopian capital Addis Ababa in the presence of UN chief Ban Ki-moon.
"It is my hope that the framework will lead to an era of peace and stability for the people of the Democratic Republic of Congo and the region," Ban said.
But he added: "It is only the beginning of a comprehensive approach that will require sustained engagement."
The accord aims to encourage the reform of weak institutions in the DRC, central Africa's largest nation, and calls for countries in the region to stop interfering in each other's affairs.
After the signing, US ambassador to the UN Susan Rice warned it was "imperative that the DRC's neighbours respect its sovereignty and territorial integrity by preventing external support to armed groups, which is a violation of international obligations".
The accord also provides for changes to the UN's 17,000-strong MONUSCO peacekeeping mission. That may lead to creation of a special UN "intervention brigade" to fight rebel groups and support political reforms, and the appointment of a UN special envoy.
South African President Jacob Zuma described the creation of the brigade, which will total 2,500 troops, as a realistic way to quickly restore security.
DR Congo's mineral-rich east has been ravaged by conflict involving numerous armed groups for the past two decades, with new rebel movements spawned on a regular basis.
Neighbouring states have regularly been accused of meddling in the eastern DR Congo, with the illegal extraction of its valuable minerals one of their motivations.
The latest surge in violence erupted last year and culminated in the rebel March 23 movement (M23) -- made up of largely Tutsi former soldiers -- briefly seizing the key town of Goma in November.
At the UN headquarters in New York on Sunday, the Security Council again expressed concern at the deteriorating situation in eastern DR Congo.
Its members renewed their condemnation of the M23 group, one of the key targets of the UN accord.
"They reiterate their demand that the M23 cease immediately attempts to establish an illegitimate parallel administration," said a statement released by the council.
Rwanda and Uganda, both signatories of the new accord, have been accused by UN experts of backing the M23, which launched an uprising against the DR Congo government last year.
Both countries have denied the charge and at Sunday's ceremony, Rwandan President Paul Kagame welcomed the accord.
"Today's agreement is an important step and opportunity in reaffirming our commitment to regional peace," he said.
"Nothing would be of greater benefit to Rwanda than real progress towards regional peace and stability."
Kagame and the presidents of the DR Congo, South Africa, Mozambique, Congo and Tanzania were present for the signing of the agreement.
Envoys represented Angola, Burundi, the Central African Republic, Uganda and Zambia.
The African Union's commissioner for peace and security Ramtane Lamamra welcomed the deal. So too did the European Union, in a statement from foreign policy chief Catherine Ashton.
A first attempt to get the peace agreement signed last month on the sidelines of the African Union summit was called off at the last minute.
The DR Congo is the biggest and most populous country in central Africa and has enormous but largely untapped potential mineral wealth including copper, oil, diamonds, gold, silver, zinc and uranium.