The plan will require Tokyo to ease its decades-old ban on arms exports as it is expected to involve exports of Japanese-made parts to the United States, the Kyodo news agency quoted government sources as saying.

The two countries have been engaged since 1999 in joint technological research on a missile defence system.

Tokyo has now decided to move the programme to a "development stage" under strong pressure from Washington, the report said.

No government officials were immediately available to comment on the report Monday, a public holiday.

A panel of security advisors to Prime Minister Junichiro Koizumi this month proposed that the arms export ban be removed with an eye on the joint parts development, the report added.

The joint research was launched a year after North Korea fired a suspected ballistic missile over Japan and into the Pacific.

In 1976, Tokyo banned arms exports to all nations, but made an exception in 1983, following a request from Washington, to allow "technology" exports to the United States.

The joint research covers four areas -- infrared ray sensors for identifying and tracking missiles, high-performance shields to protect interceptor warheads from air-attrition heat, second-rocket propulsion units, and kinetic warheads for destroying warheads of incoming ballistic missiles.

Separate to the joint research, Tokyo has already decided to purchase a US-made missile defence system.

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