U.N. diplomats say peace talks between the Democratic Republic of Congo's government and M23 rebels have stalled after making some progress.
After four days of negotiations, envoys to the talks say the sides have agreed on eight of 11 issues in a draft peace agreement. They say the sides remain apart on questions of amnesty for the rebels, integration of armed forces, and security arrangements.
Envoys Martin Kobler and Mary Robinson addressed the U.N. Security Council by videolink Monday, after attending the peace talks in Uganda's capital, Kampala.
Kobler, the secretary-general's special representative to the DRC, said it is "regrettable" the sides could not reach an overall deal. In a comment aimed at M23, he urged the rebels to "sort out" remaining issues "without delay."
He also said that in recent days, U.N. peacekeepers have observed what he called a "considerable military build-up" on both sides of the front line.
M23 emerged last year to take over territory in Congo's North Kivu province. The group consists of rebel fighters who joined the Congolese army in a 2009 peace deal but defected and regrouped after complaining of poor treatment.
The U.N. is pressing for a peace deal as part of efforts to stabilize the eastern DRC.
North Kivu and nearby provinces have endured years of fighting between the government and various militia and rebel groups. Much of the fighting is over control of the area's rich mines.
U.N. experts have accused Rwanda and Uganda of supporting M23, an allegation both nations deny.