China is opening up its military-run manned space programme to foreign nations, seeking its own alliances as US concerns see it excluded from the international space station project, analysts say.

The Asian country this week successfully carried out its first docking in orbit, and the Shenzhou VIII spacecraft involved in the delicate manoeuvre carried German life science and microgravity experiments on board.

It is just one small step, but it is the first time any other country has been given access to China's flagship manned spaceflight programme since it began 20 years ago.

In contrast, Beijing readily co-operates internationally in other fields such as astrophysics and Earth observation.

Isabelle Sourbes-Verger, a China space programme expert at France's National Centre for Scientific Research, said the internationalisation of its manned flights showed China was no longer playing catch-up with other nations.

Germany had an interest in broadening its choice of launchers for its regular microgravity experiments, she said, adding that "nothing was forcing the Chinese to open up their programme to external partners".

The implication, she said, is that Beijing no longer sees the field as primarily the domain of the military.

The final frontier has long been an arena of competition between global superpowers, as evidenced in the 1950s and 60s by the race between Moscow and Washington to be first in orbit, to put a man into space and go to the Moon.

Asia's new superpower began its manned exploration of space in 1990, on the back of bought-up Russian technology as the Soviet Union broke up, and placed the project under the purview of the People's Liberation Army.

It now sees the programme as a symbol of its own global stature and the Communist Party's success in turning around the fortunes of the once poverty-stricken nation.

China is only the third country to send humans into space and has announced plans to build a space laboratory by 2016 and a permanent space station by 2020.

A Chinese astronaut trainer is among six volunteers who will emerge Friday into the outside world after spending almost 18 months in isolation at a Russian centre to test the effects on humans of a flight to Mars.

But unlike the Russians, Europeans and Japanese, China is not part of the multi-billion-dollar International Space Station project, which began before Beijing had developed an advanced space programme of its own.

It still remains excluded because of American concerns over its intentions, experts say.

"It's all because of resistance from the USA," said Morris Jones, an Australian based expert on the Chinese space programme. "This is mainly due to security reasons, but it also involves politics."

Dean Cheng, a research fellow at the Asian Studies Center of the Washington-based Heritage Foundation think-tank added: "There are a variety of concerns, not just security in the military sense, but also issues of technology transfer and information access."

Illustrating these concerns, two US congressmen blasted the White House and NASA this week for "dangerous" cooperation with China, saying technology transfer had greatly enhanced Beijing's missile and rocket capability.

Undaunted, Wu Ping, spokeswoman for China's manned spaceflight programme, said Beijing would seek "concrete co-operation and active exchanges with all the countries of the world on the basis of openness and transparency".

How far that co-operation will extend remains unclear, however, and in space it can be a long march to the future.

Cheng pointed out that extensive preparations were needed before a Cold War-era rendezvous between American astronauts and Soviet cosmonauts took place in 1975.

"The Apollo-Soyuz mission required years of careful negotiation between the US and the USSR," he said.