Tokyo and Washington are contemplating Japanese participation in a multinational project to develop the F-35 stealth fighter, sources in both governments said Tuesday.

The move is intended to clear the way for Japan to adopt the F-35 as its mainstay fighter jet, because countries not participating in the project won't be allowed to acquire it at an early date.

Tokyo's participation would be limited to developing components to be provided exclusively to the Air Self-Defense Force so as not to conflict with Japan's principles of banning exports of weapons and arms technology, the sources said.

The U.S. is considering allowing Japan to take part in the program even without assurances from Tokyo that it will procure the F-35, they said.

The F-35 is being developed by the United States, Australia, Britain and other countries. It is due to be available for operational use in the mid-2010s. Countries involved in the joint project are expected to be able to acquire the fighter on a preferential basis.

Japan initially aimed to acquire the U.S. F-22 stealth fighter to replace its aging F-4EJ fighter fleet, but U.S. law currently prohibits exports of the F-22 and the U.S. has announced it will halt production of the fighter.

Japan has also studied other planes, such as the F/A-18 and F-15FX produced by the U.S., and the Eurofighter, produced by a consortium of European manufacturers.

The government is likely to incorporate the plan to acquire the F-35 in new defense policy guidelines and the medium-term defense buildup plan to be adopted next December.

The government decided in October to delay its adoption by one year partly to reflect the policies of the Democratic Party of Japan and its coalition partners.