WASHINGTON: The Pentagon and Lockheed Martin Corp , its largest supplier, sought on Friday to shoot down criticism of their $299 billion F-35 Joint Strike Fighter program, the costliest planned US arms buy ever.

Published reports that Russian-built Sukhoi fighter jets thrashed the F-35 in simulated dogfights last month are "just flat false," Air Force Maj. Gen. Charles Davis, the Pentagon official in charge of the program, said in a teleconference hastily called by Lockheed to rebut negative publicity at a critical juncture for the program.

Development of the family of radar-evading, multi-role, single engine F-35 fighters was co-financed by Britain, Italy, the Netherlands, Turkey, Canada, Australia, Denmark and Norway.

Each of these countries is within a couple of months to a couple of years of making F-35 procurement decisions, and some people with unspecified "agendas" may be maneuvering, Davis said.

F-35 competitors include Saab's Gripen, the Dassault Rafale, MiG-35 and Sukhoi Su-35, and the Eurofighter Typhoon, made by a consortium of British, German, Italian and Spanish companies.

The West Australian newspaper reported earlier this month that F-35s had been "clubbed like baby seals" by simulated Sukhois at war games in Hawaii last month.

Tom Burbage, general manager of the F-35 program for Lockheed Martin, said in the teleconference, "We've been able to put the issue in Australia to bed." He said Australia's prime minister had been among those troubled by the report.

Davis countered that the exercise at issue, Pacific Vision 2008, did not even address air-to-air combat effectiveness, dealing instead with logistics issues around the Pacific Rim.

Citing U.S. Air Force analyses, he said the F-35 is at least 400 percent more effective in air-to-air combat capability than the best fighters currently available in the international market, including Sukhois.

Davis and Burbage also took aim at a highly critical guest column in the September 10 issue of Jane's Defence Weekly, a trade publication, by industry-watchers Winston Wheeler and Pierre Sprey, who helped shape Lockheed's F-16 fighter.

Wheeler and Sprey tarred the F-35 as a "dog," calling it overweight, underpowered and, with a payload of only two 2,000-pound bombs in its bomb bay, "hardly a first-class bomber either."

As a close-support attack aircraft, they wrote it is too fast to see the tactical targets it is shooting at; too delicate and flammable to withstand ground fire; and lacking the "endurance" to loiter usefully over friendly ground forces for sustained periods.

In a rebuttal statement, Lockheed said the F-35 was a "racehorse, not a 'dog'," with unprecedented combat advantages, including the most powerful engine ever installed in a fighter.

The first F-35, a conventional take-off and landing version, began its flight testing program on December 15, 2006.

After the June 11 maiden flight of a short take-off, vertical landing model, the Pentagon's top arms buyer, John Young, said the program was more mature than comparable ones at this stage of development "in terms of quality, software, testing and manufacturing readiness."

Lockheed's chief F-35 subcontractors are Northrop Grumman Corp and BAE Systems Plc. Two rival, interchangeable F-35 engines are under development. One is built by United Technologies Corp's Pratt & Whitney unit; the other by a team of General Electric Co and Rolls-Royce Group Plc.

The United States currently plans to buy a total of 2,443 F-35 models -- including 1,763 for the US Air Force and 680 for the Marine Corps and Navy together. It is the costliest U.S. arms program ever at a projected $299 billion.

Hundreds of others may be sold overseas to replace a range of fighters, including Lockheed F-16s and Boeing Co F-18s.

Davis has said the F-35 is on course to become a $1 trillion venture worldwide through 2065, when the last scheduled to be built would reach the end of its projected service life.

One trillion dollars is "what it costs to develop, buy, upgrade, sustain and fly more than 3,000 airplanes through their entire scheduled life cycle," he told Reuters in July, referring to the projected world fleet.