ADDIS ABABA -- The African Union resolved late Friday to use its good offices to try to ease tension between Sudan and Eritrea in the wake of accusations by Khartoum that Asmara was backing Sudanese rebels.

The AU's Central Organ for Conflict Prevention, Management and Resolution also called on the leaders of both countries to "show restraint" and "abstain from all acts that might aggravate tension," the AU said in a statement. The AU expressed its "deep concern" over this tension and "and the risks it places on peace and security in the region." On Friday, a regional governor in eastern Sudan said the army was tightening its siege of the town of old Rassai, which lies on the border with Eritrea, "to clear it of rebel and Eritrean forces."

Eritrea has repeatedly denied helping the Sudanese rebels, AFP reported.

Amara Essy, the interim president of the AU Commission, called Friday on both countries to work with the AU good offices delegation, which plans to visit Asmara and Khartoum next week.