WASHINGTON -- CIA officials proposed activating a plan to train teams to kill Al Qaeda leaders abroad when managers within the agency told Director Leon Panetta about the secret program last month, two U.S. officials told The Washington Post.

The plan to assassinate terror leaders, which was terminated in 2004 by Director George Tenet but resurrected by his successors, was brought to light after proposals to initiate a "somewhat more operational phase," the Post reported on Thursday.

National Intelligence Director Dennis Blair defended Panetta's decision on Wednesday to cancel the program because, according to the paper, serious questions were raised among officials about its "effectiveness, maturity and level of control."

Officials told The Associated Press that Tenet ended the secret program because the agency could not work out its practical details. The officials spoke on condition of anonymity to discuss the classified program.

Porter Goss, who replaced Tenet in 2005, restarted the program, the former officials said. By the time Michael Hayden succeeded Goss as CIA chief in 2006 the effort was again flagging because of practical challenges.

Panetta drove the final stake into the effort in June after learning about the program. He called an emergency meeting with the House and Senate Intelligence committees the next day, informing lawmakers about the program and saying that as vice president Dick Cheney had directed the CIA not to inform Congress about the operation.

The CIA declined to comment on the officials' comments.

One former senior intelligence official said Wednesday that the idea never quite died because it was a capability -- the details of which remain classified -- that the CIA wanted in its arsenal. But as time wore on, the official said, its need became less urgent.

Another former official said that the CIA's reliance on foreign intelligence services and on drone-launched missile strikes proved over time to be less risky yet effective in targeting Al Qaeda chiefs for death or capture. President George W. Bush authorized the killing of Al Qaeda leaders in 2001.

According to one congressional official, the agency spent more than $1 million over the eight years that the CIA considered launching the hit teams. The official would not detail the exact amount or how it was spent.

The House Intelligence Committee is laying the groundwork for a possible investigation of the program and its concealment from Congress. In late June it asked the CIA to provide documents about the now-canceled program to kill Al Qaeda leaders.

Agency officials say it is complying with the request. Panetta has at the same time ordered a thorough internal review of the program.

The committee will likely focus on how much was spent on the effort, whether any training was conducted and whether any officials traveled in association with the program, a congressional official said. Those factors would determine whether the program had progressed enough to require congressional notification.

House Intelligence Committee Chairman Silvestre Reyes is expected to decide as early as this week whether to press ahead with a full investigation.

The Associated Press contributed to this report.