China on alert for Taiwan war

Such a conflict could pin United States allies in the area, such as Japan and Australia, between their treaty obligations to Washington and a reluctance to alienate China, which is a growing political and economic force in the region.

China’s rubber-stamp parliament unanimously passed the law to authorise an attack to stop Taiwan from pursuing formal independence, a day after president Hu Jintao told the Chinese military to be prepared for war.

The ceremonial National People’s Congress in Beijing approved the legislation despite US calls for restraint and warnings by Taiwan that it would damage regional stability and fragile ties between Beijing and Taipei.

An outbreak of hostilities would be a severe blow to stability in East Asia, possibly prompting a response from the US - which has 50,000 troops in Japan and 35,000 in South Korea - to defend Taiwan.

The White House said China’s threat to use force was an "unfortunate" development that could increase tensions.

Scott McClellan, the White House press secretary, said: "It does not serve the purpose of peace and stability in the Taiwan Strait. We believe it runs counter to recent progress in cross-Strait relations."

Russia threw its support behind China, saying it could understand the motives. It considered the question of Taiwan an internal matter for China.

Junichiro Koizumi, the Japanese prime minister, said: "I want the two sides to work hard towards a peaceful solution, so there will not be any negative impact."

In Australia, Alexander Downer, the foreign minister, said his government would consult with the US, as required by the 54-year-old ANZUS treaty, if a Chinese attack on Taiwan triggered an American military response.

But whether Australia would join the fight was a separate question, he said.

Taiwan warned that the anti-secessionist law is a serious threat to security in Asia.

About 30 protesters - mostly pro-independence MPs - demonstrated outside the Taiwanese parliament in Taipei, burning a Chinese flag and chanting anti-China slogans.

Joseph Wu, the island’s senior policy-maker for China relations, said: "It will be difficult to maintain true peace and stability in the Asia-Pacific region," because China refused to renounce the use of force against Taiwan.

Mr Wu added the law "provides a blank cheque" for China to annex Taiwan.

Taiwan and China split in 1949, but the communist mainland claims the self-ruled island as its territory and has threatened to attack if it tries to make its de-facto independence permanent.