Japan passed a new law Wednesday allowing the use of space programmes for defence, an official said, reversing a decades-old policy amid increasing concern about military threats in the region.

While Japan has no current plans for a new defence project in space, experts say the law could clear the way for the launch of early-warning satellites.

The move comes amid growing concerns here about North Korea's ballistic missile development and China's military and space programmes.

The opposition-controlled upper house voted 221 to 14 to revise a 1969 parliamentary resolution limiting Japan's use of space to non-military applications, an upper house official said.

The bill was already approved by the lower house last week.

The law says that the use and development of space should be done "in accordance with the pacifist spirit of the Japanese constitution" and benefit the security of Japan and the international community.

It aims to remove any legal obstacles to building more advanced spy satellites and to help innovation in the country's space industry.

The opposition Japanese Communist Party was against the bill, fearing it would lead to a stronger military.

But Chief Cabinet Secretary Nobutaka Machimura dismissed concerns that the law could mean Japan's defence capabilities exceed the constitutional limits.

"Who in the world would think Japan would try to invade another country by using satellites? It's impossible," the top government spokesman told a press conference, Kyodo News reported.

Proponents of the legislation argue that it is necessary as Japan has fallen behind other nations in space technology, particularly as China moves to capture space business in Asia, Africa and Latin America.

Japan's US-imposed post-World War II constitution says the country will never again wage war. Japanese troops have not fired a shot in anger since 1945, although the country has one of the world's largest defence budgets.

Japan has stepped up military research after North Korea stunned the world in 1998 by firing a missile over the Japanese mainland into the Pacific.

China also alarmed Japan last year by conducting a test to shoot down a satellite.

Japan has been stepping up its space programme and is now conducting the most extensive probe of the moon since the US Apollo missions of the 1960s and 1970s.