Inspite of strenuous efforts by the world's largest defence contractor, Lockheed Martin, to contradict reports that the Joint Strike Fighter programme was heading for substantial cost and time overruns, it has now been confirmed in Pentagon testimony before the US Congress's Senate Armed Services Committee that the cost of the programme has increased 60 to 90 per cent in real terms since 2001.

Even as the Pentagon steps into overdrive trying to reassure stakeholders, which are three armed services of the United States and eight partner nations that it will take all required steps to deal with the problems, Congressional auditors have said the program was likely to haemorrhage in terms of costs and suffer time overruns.

The F-35 Lightning II is a single-engine stealth fighter designed primarily for ground attack roles. It is meant to form the backbone of American and allied air forces over the next several decades.

The US Air Force, the US Navy and the US Marine Corps plan to buy 2,443 of the planes. Eight allied nations have also invested in the programme, and though not committed to buy any, are ready to purchase hundreds of additional planes.

The JSF project has eight partner countries and two Security Cooperative Participants (SCPs). The partners include the United Kingdom, Italy, Netherlands, Turkey, Canada, Australia, Denmark, and Norway. The two SCPs are Israel and Singapore.

The latest cost and schedule estimates are likely to embarrass not just Lockheed Martin, but the respected defence secretary, Robert M Gates, who promoted the new jet at the expense of another costly defence acquisition, the F-22 Raptor air dominance fighter.

Christine H Fox, a top Pentagon official said at Thursday's hearing that the estimated price of each F-35 had jumped to $80 million to $95 million, as measured in 2002 dollars, from $50 million when Lockheed Martin was awarded the contract in 2001. This would equal to $95 - $113 million for each plane in current dollars.

Secretary Gates recently fired the general in charge of the programme and announced measures aimed at getting the programme back on track.

Michael Sullivan, an analyst at the Government Accountability Office, said the programme could eventually cost $323 billion, near to double the original $200 billion estimate. He also said that though recent changes could help ease problems, ''further cost growth and schedule extensions are likely.''