Nairobi/Khartoum - The United Nations special envoy for Sudan, Ashraf Jehangir Qazi, on Friday expressed concern over the situation around the southern city of Abyei, calling for protection of civilians and civilian infrastructure in the disputed oil region.

Qazi made the call despite a ceasefire that was agreed upon on Thursday by Sudanese government forces and former fighters of the southern Sudanese resistance group, SPLA.

Thousands of people in recent days have fled fighting between government and rebel forces in Abyei, which lies on the border between northern and southern Sudan.

UN personnel have also been removed from the area due to the worsening security situation.

Qazi said an "immediate ceasefire and a withdrawal of all armed groups from Abyei" was required.

The developments in the past few days had shown that the problems in the oil-rich region could cause the greatest difficulties in the implementation of the peace agreement between the north and the south, he added.

The 2005 peace agreement ended the bloody civil war between the Arab-dominated central government and the SPLA rebels in the south. In 2011, the population of the south is to decide in a referendum whether they will seek full independence from Sudan. (dpa)