Updated

United Nations Secretary-General Ban Ki-moon is urging immediate implementation of a cease-fire agreement in northern Mali.

Ban says there should also be political negotiations between the government and Tuareg rebels who still control the key town of Kidal.

The U.N. chief said in a report to the Security Council circulated Friday that the resumption of hostilities last month has resulted in "an altered security landscape in the north of Mali with risks for international security."

He said terrorist and armed groups operating in the north pose a significant threat to civilians, U.N. peacekeepers and the delivery of humanitarian aid.

In June 2013, Tuareg leaders signed a cease-fire agreement with the government requiring the rebels to garrison their fighters prior to disarmament — which hasn't happened.