Defense Secretary Robert Gates said on Thursday a move by US lawmakers to reject his advice and fund the production of a dozen more F-22 fighters was a "big problem."

The US House Armed Services Committee on Wednesday passed an amendment extending production of the F-22 Raptor, a sophisticated stealth fighter aircraft the Pentagon has sought to scrub.

Lawmakers voted 31 to 30 to provide 369 million dollars over two years to purchase parts to construct 12 more of the Raptors, built by Lockheed Martin and Boeing.

"I would say it's a big problem. I have a big problem with it," Gates told reporters when asked about the committee's decision.

The vote was contrary to his recommendations and President Barack Obama's proposed budget, he said.

Asked if the move, which must still be approved by the full House of Representatives and the Senate, would be vetoed by the president, Gates said: "I'm not going to go that far at this point. I think describing it as a big problem suggests where I am on it."

Gates had sought to cap production at 187 jets, meaning only four more would be built. But many Republicans balked at the administration's plans.

The F-22 program has its origins in the Cold War, and its advocates say the Raptor is crucial to maintaining US air superiority as China and other possible adversaries invest in modern fighters.

But critics say a larger fleet of F-22s is unnecessary at a time when funds are needed for weapons more suited to counter-insurgency campaigns like those in Iraq and Afganistan.

The Raptor has not been deployed to Iraq or Afghanistan.

Gates has instead proposed a major investment in F-35 Joint Strike Fighters.

The defense secretary rejected criticism that he has moved away from conventional weaponry in favor of irregular or counter-insurgency capabilities.

"You know, a trillion dollars for the Joint Strike Fighter, a fifth-generation fighter that has some capabilities the F-22 does not, is not a trivial investment in the future," Gates said.

The defense secretary also said he would go ahead with plans to open competition for a politically sensitive contract to replace the aging fleet of air refueling aircraft by "mid-summer."

The Pentagon awarded the 35-billion-dollar contract for 179 aircraft to the EADS/Northrop Grumman team in February 2008, but Boeing successfully challenged the decision with the Government Accountability Office (GAO).