The Joint Strike Fighter next generation warplane for US and allied forces may end up costing more than 100 million dollars per plane, a Pentagon official told Congress Thursday. This would mean the final cost would be double the initial estimate when the contract was awarded in 2001 for the JSF, the costliest weapons program to date for the Pentagon. Christine Fox, director of the Defense Department's Cost Assessment and Program Evaluation office, told the Senate Armed Services Committee that "the current program estimate based on jet two numbers will be somewhere between 80 and 95 million dollars in constant year (2002) baseline dollars. We are refining that estimate now." That would mean between 95 million and 113 million dollars per unit in current dollars, irritated lawmakers pointed out. "The taxpayers are a little tired of this, and I can't say I blame them," Senator John McCain told the hearing. US officials now estimate Washington's bill for the program will be more than 300 billion dollars. Washington expects to buy more than 2,400 of the new aircraft to update the fleet of warplanes for the Air Force, Navy and Marine Corps. The plane also known as the F-35 to be manufactured by Lockheed Martin is expected to be ready in 2016, well behind the original schedule of first deliveries in 2012. The fighter's development was funded by an international consortium led by the United States. Britain, Australia, Canada, Italy, Denmark, Turkey, Norway and the Netherlands have signed on for the next phase of production and follow-on development of the fighter.