UNITED NATIONS -- The UN Security Council on Monday "condemned in the strongest terms" the deadly attack in the disputed oil-rich area of Abyei on the Sudan-South Sudan border, which left a top tribal chief and a UN peacekeeper dead, and three others injured.

In a press statement released here, the 15-member Council expressed its condolences to the families of those killed in the attack and reiterated its full support for the United Nations Interim Security Force for Abyei (UNISFA) by urging all parties in the Abyei area "to exercise maximum restraint, to cooperate fully with the mission, and to use mechanisms they have put in place to facilitate an effective investigation" into the acts of violence.

The Ngok Dinka Paramount Chief DengKuol Deng and an Ethiopian peacekeeper of UNISFA were killed on Saturday in an attack by a Misseriya assailant on a UNISFA convoy in Abyei, which straddles the border between Sudan and South Sudan and is claimed by both countries. The Dinka Ngok tribe is a branch of the Dinka, a dominant tribe in South Sudan.

The statement said that the UN Security Council "welcomed the government of Sudan's announcement of an urgent, transparent, thorough, and fair investigation into the incident as well as its pledge to bring the perpetrators to justice." The council also welcomed the government of South Sudan's public statements and " its continuing commitment to UNISFA."

UNISFA was authorized by the UN Security Council in November 2012 to group a maximum of 4,200 military personnel, 50 police personnel, and appropriate civilian support. It currently has 3, 977 uniformed personnel, including 3,827 troops and 140 military observers.

The most powerful UN body also underlined "the critical importance of immediate and full implementation" of the agreements reached between Sudan and South Sudan as well as the need for continued hard work by all relevant parties to resolve the details and outstanding issues that remain to be agreed upon, including the final status of Abyei.

In March, Sudan and South Sudan agreed to resume cross-border oil flows and defuse tensions which have plagued them since South Sudan's independence from Sudan in July 2011. But the two countries have not yet reached an agreement so far over the ownership of the oil-rich Abyei, which is reportedly inhabited by the Dinka tribe allied to South Sudan and the Misseriya, an Arab tribe following Sudan.