Kabul, Afghanistan ? The United Nations — already forced out of Iraq by suicide bombers — may have to abandon its two-year effort to stabilize Afghanistan because of rising violence blamed on the Taliban, its top official here warned Friday in an interview with The Associated Press.

Lakhdar Brahimi said his team could not continue its work in this war-ravaged nation unless security improves. He called for more foreign troops to halt attacks that have killed at least 11 aid workers across the south and east since March.

“Countries that are committed to supporting Afghanistan cannot kid themselves and cannot go on expecting us to work in unacceptable security conditions,” Brahimi said.

“They seem to think that our presence is important here. Well, if they do, they have got to make sure that the conditions for us to be here are there,” he said. “If not, we will go away.”

NATO, which commands a 5,500-member peacekeeping force in the capital, Kabul, has agreed in principle to expand into the provinces. But nations have been slow to come forward with pledges of troops and equipment.

In addition to the peacekeepers, a U.S.-led force of some 11,700 soldiers are still pursuing Taliban remnants, followers of al-Qaida and fighters loyal to renegade warlord Gulbuddin Hekmatyar.

White House spokesman Scott McClellan, responding to Brahimi’s comments, said the Bush administration hoped the world body remained in Afghanistan.

“Our military and those working with us there as well in the coalition efforts have done an outstanding job to improve the security situation,” McClellan said.