U.S. and other anti-terrorism coalition officials are beginning to believe that Usama bin Laden has fled Afghanistan for Pakistan, two members of the Senate Intelligence Committee said Sunday.

Sen. John Edwards, D-N.C., who is traveling with other senators in the region, told Fox News Sunday that Uzbekistan's military intelligence service believes bin Laden has crossed the border into Pakistan. Uzbekistan, like Pakistan, borders Afghanistan and has been a U.S. ally in the fight against the Taliban and Al Qaeda.

"I fully expect the Pakistanis will do everything they can to help us locate bin Laden," Edwards said.

Intelligence Committee Chairman Sen. Bob Graham, D-Fla., said bin Laden and other top officials have probably escaped Afghanistan, but no one is certain.

"Increasingly as our efforts to get them in Afghanistan have been futile, there is a greater sense that they have, in fact, escaped, and are probably in one of those tribal territories just over the border into Pakistan," Graham said from Miami on ABC's This Week.

Top military officials have said they don't know where bin Laden and Mullah Mohammed Omar, the Taliban's supreme leader, are.

Bin Laden was thought to be in the Tora Bora region of Afghanistan, but he has not turned up in searches by U.S. and anti-Taliban forces there. Omar was most recently thought to be near Baghran, northwest of Kandahar, but Afghan officials now say they believe he escaped.