The new US ambassador, Zalmay Khalilzad, an Afghan-born diplomat who is to be sworn in on Monday and depart for Kabul on Tuesday, said more help is needed from Afghan citizens particularly along border regions of Pakistan that the elusive bin Laden and top aides might be crossing into.

"We're going to redouble our efforts," Khalilzad told a group of reporters. With new funding for Afghanistan approved by Congress, the United States plans to "take the fight to the Taliban extremists and to go after the al Qaeda leadership," he said.

The Arabic television station Al Jazeera a month ago broadcast two audio tapes purportedly from bin Laden that vowed more suicide attacks inside and outside the United States and warning that all countries backing Washington over Iraq were targets.