UPDATE 1-U.S. senate panel "deeply concerned" by F-35 costs

By Jim Wolf
WASHINGTON, Dec 16 (Reuters) - The U.S. Senate Armed Services Committee said it was "deeply concerned" about growing costs and apparent delays in Lockheed Martin Corp's (LMT.N) F-35 fighter program, the Pentagon's costliest acquisition.
Discussion with top Pentagon officials took place on Wednesday behind closed doors of "strategy to keep costs down and to have development brought back to its planned schedule," the panel's chairman, Democrat Carl Levin of Michigan, and its top Republican, John McCain, said in a joint statement.
"We, along with other members of the Senate Armed Services Committee, are deeply concerned about the growing costs and apparent delays in the F-35 program," the statement said.
"Today's briefing is one step in continuing close oversight of the program, which is not only the largest acquisition program under way, but probably the most complicated and challenging."
The F-35 is being built in three different versions for the U.S. Marine Corps, Navy and Air Force. Eight international partners have co-financed the jet, designed to switch quickly between air-to-ground and air-to-air missions while still flying.
The panel was to have been briefed by William Lynn, the deputy defense secretary, and Ashton Carter, the Pentagon's chief weapons buyer among others. The hearing was originally scheduled to have been public, but was taken behind closed doors because it involved Lockheed's proprietary information, a committee aide said.
The United States currently plans to buy a total of 2,443 F-35 aircraft, the Pentagon's costliest acquisition at a projected $300 billion over the next two decades.
The radar-evading aircraft is in early production.
Air Force Secretary Michael Donley told the Reuters summit on Monday he expected a shake-up in the program, including "adjustments in schedule."
"And there will be pushing and pulling of fighters across different years" through 2014, the scheduled end of the development phase, as a result of recent program reviews, he added. (Reporting by Jim Wolf; editing by Andre Grenon)