Reps. Howard Berman, D-Calif., and Nita Lowey, D-N.Y., issued a joint statement expressing concern the proposed funds for the F-16s would divert resources away from "more effective counter-terrorism tools like helicopters, (tube-launched, optically tracked, wire-guided) missiles and night-vision goggles."

"We have requested a hold on the administration's planned reprogramming pending additional information," the statement continued.

The United States has been urging Pakistan to step up its counter-terrorism efforts in the Federally Administered Tribal Areas along the border with Afghanistan, believed to be a stronghold for the leadership of al-Qaida.

The plans to divert funds raised questions on Capitol Hill last week regarding the applicability of F-16s in the counter-terrorist campaign in the region.

The joint statement from Berman, chairman of the House Foreign Affairs Committee, and Lowey said a foreign operations bill passed in Congress last December "specifically required that military aid to Pakistan be used for counter-terrorism and law enforcement activities directed against al-Qaida and the Taliban."

The lawmakers said they would ask Congress to provide Pakistan with $200 million in aid to help the government in Islamabad cope with rising food and energy prices.