A Democratic lawmaker demanded Thursday that the Bush administration address security concerns in Congress over a proposed sale of F-16 fighter jets to Pakistan.

Rep. Tom Lantos emphasized in an interview that he supported the $5 billion proposal, "but my support is contingent on providing the United States with total security with respect to the non-leaking of any of our high-tech capabilities to any other party."

Lantos, the top Democrat on the House of Representatives' International Relations Committee, said that after speaking Thursday with top State Department officials, he believed those concerns could be resolved.

Lawmakers' concerns apparently led to the postponement of a congressional hearing Thursday meant to examine the jet sale. The hearing was rescheduled to next week.

Lawmakers worry that China, which has close military ties with Pakistan, might gain access to F-16 technology.

Lantos said that "in view of the very unfortunate A.Q. Khan history, we have to be absolutely convinced that the provisions in place will prevent any conceivable leakage of technology to anybody."

Khan, revered as the father of Pakistan's nuclear bomb, has admitted to running a nuclear-smuggling ring for years.

CountryWatch: Pakistan

State Department spokesman Sean McCormack said that officials have had extensive consultations for more than a year with lawmakers and their staffs. He said they were willing to continue to work closely with Congress.

Late last month, the Bush administration notified Congress that it had approved the sale of 18 new fighter jets to Pakistan, a major ally in the U.S. fight against terrorism, and gave lawmakers 30 days to consider the deal. The administration usually provides Congress an informal "pre-notification" period of 20 days before the formal 30-day notification to consult on the deal.

Lantos said that move went against 30 years of precedent in dealings between the administration and Congress. "We are a co-equal branch of government, and we, for the sake of national security, need to be treated as such," he said.

The Pakistan package includes an option to purchase another 18 F-16 fighter jets, an offer to modernize 26 used aircraft already in Pakistan's arsenal, as well as logistical and other support. Lockheed Martin Corp. produced the jets.

The proposed sale to Pakistan comes as the White House pushes for congressional endorsement of a landmark nuclear cooperation deal with India.

Pakistan and India have fought three wars since their 1947 independence from Britain — two over Kashmir, a Himalayan state that both claim in its entirety but that is divided between them by a U.N. line of control.

In an interview Wednesday with The Associated Press, Pakistani Foreign Minister Khurshid Kasuri rejected claims that F-16 technology would be used irresponsibly.

"Of course we have a strong relationship with China. That's not a secret. But when we enter into an obligation, it's in our own interests to fulfill it," Kasuri said. "Pakistan is a very responsible country."