The US Air Force has estimated that export version F-22 fighters would cost Japan about $250m each if the present US ban on its export is lifted.

The F-22, US defence classified equipment, is a multi-mission fighter that can simultaneously carry out air-to-air and air-to-ground combat missions in face of multiple airborne and ground-based threats.

Japan has long been interested in buying two squadrons of its own F-22s that translates into orders for 40 to 60 fighters.

The US Air Force is no longer opposed to F-22 exports and is planning to lift the ban in the face of recent North Korean missile launches, continued interest by Japan and the impending shutdown of the F-22 production line, Reuters reports.

The export may also open up the possibility for resuming F-22 production for the US Air Force in future, which is expected to halt in 2009 with production of 191 planes due to budget constraints.

Japan seems to be willing to pay the cost of modifying the sophisticated fighter jets for export that would amount to about $1bn, Reuters says.