Members of a House-Senate conference committee have reached a preliminary agreement that would prohibit the Air Force from leasing refueling aircraft from Boeing Co., congressional sources familiar with the deal said yesterday.

The deal will not be final until the committee completes its work, which stretched into last night. But language agreed on during its deliberations on the 2005 defense authorization bill would prohibit the lease and subsequent purchase of Boeing 767 tankers and allow the Air Force to buy up to 100 tankers, the sources said. It was not clear last night whether the Air Force would be required to hold a competition before buying the aircraft.

Sources familiar with the committee's work described the agreement, speaking on condition of anonymity because the committee was still working. Rep. Duncan Hunter (R-Calif.), chairman of the House Armed Services Committee, confirmed late yesterday that a deal had been reached.

John Ullyot, spokesman for the Senate Armed Services Committee, said it was not possible to predict the outcome of the conference until the conferees finished their work. A House Armed Services Committee spokeswoman said the bill was expected to be filed early today and then voted on by the House and Senate.

The Air Force originally wanted to lease, then buy the planes from Boeing in a $23 billion deal, but critics said the program was expensive and unnecessary. The program was derailed last December when Chicago-based Boeing fired former Air Force procurement officer Darleen A. Druyun for negotiating employment with the company while overseeing Boeing's work at the Air Force, including negotiating the tanker contract.

Last week, Druyun was sentenced to nine months in prison after admitting she inflated the price of the deal as a "parting gift" before her Pentagon retirement to ingratiate herself with Boeing.

The Pentagon has said a decision on how to move forward on the tanker program would not be made until after the election, pending studies of alternatives. The authorization bill agreement, if passed by the House and Senate, would prevent the department from reverting to the original program, congressional sources said.

The Air Force has not reviewed the authorization bill, said spokesman Col. Dewey Ford. Boeing declined to comment.