Secretary-General Ban Ki-moon is warning that Burundi is on the brink of a civil war that could engulf the region.

The U.N. chief expressed alarm at the "chilling" escalation in violence between government forces and armed fighters.

Ban told a news conference Wednesday his special adviser, Jamal Benomar, will travel to the region before the end of the week to press for an urgent political dialogue involving all parties.

"We must do all we can to prevent mass violence and act decisively should it erupt," he said.

Ban said the U.N. may have to ramp up its presence and activities depending on the situation.