A search is underway for two peacekeepers missing after an ambush on a joint African Union-United Nations patrol in an area of Darfur that has been the scene of recent clashes.

The patrol, which included police and military observers from the mission, known as UNAMID, was headed to the Jebel Marra region on Friday when it was ambushed by unidentified armed men.

"UNAMID strongly condemns this unprovoked attack on its peacekeepers who were carrying out an important security and humanitarian mission for the benefit of the people of Jebel Marra," the mission stated in a news release.

The attack occurred "although the mission had received assurances by belligerents that the UNAMID patrol could carry out its task," it added.

The peacekeepers and their vehicles, including three armoured personnel carriers (APCs), were seized and taken to an unknown location. The peacekeepers were released early Saturday morning along with the APCs, but all other vehicles and equipment were kept by the attackers.

In addition, "two peacekeepers are still unaccounted for and listed as missing," UNAMID stated, noting that the mission is doing everything that it can to ensure the safe and swift return of its missing personnel and of its vehicles and equipment.

UN officials have repeatedly called on all parties to the conflict in Darfur - where nearly seven years of fighting has killed at least 300,000 people and driven 2.7 million others from their homes - to exercise restraint and refrain from any action that could thwart ongoing peace efforts.

In February a cessation of hostilities agreement was signed in Doha, Qatar, between the Government and the rebel Justice and Equality Movement (JEM), in a bid to help end the conflict. All other armed movements operating in Darfur have also been urged to join the peace process without delay.