Dr Rice said the Anti-Secession Law passed by the National People's Congress last week had raised tensions across the Taiwan Strait and the United States did not want to see a unilateral change of the status quo.

'I did talk to my Chinese counterpart about hopefully taking measures that would demonstrate a willingness to reduce tension in the cross-strait environment,' she said. 'Clearly the Anti-Secession Law did increase tensions.'

But Dr Rice said Taiwan shared responsibility for easing the situation.

'Each side cannot solve the problem alone,' she said. 'They need each other to find the means to reduce tension.'

The tension demonstrated the 'unsettled nature' of China's relations in the region, Dr Rice said. Because of that, the lifting of the European Union's ban on sales of arms to China would send a wrong signal and 'might alter the military balance' in the region.

On North Korea, Dr Rice reiterated that the multilateral framework was the best way of addressing the nuclear crisis.

The ball was in Pyongyang's court to restart the stalled six-party talks.

The US and other parties had put forward reasonable offers on guarantees of security and energy supplies, and it was up to North Korea to return to the negotiating table. 'Whether the talks can restart depends on North Korea,' she said. 'Everyone is waiting and is ready to have a constructive discussion.'

Beijing, with its close relations with North Korea, had a special role to play to nudge it back to the talks, she said.

While North Korea preferred bilateral talks with the United States, the six-party negotiations provided a multilateral context since the crisis was a 'neighbourhood problem'.

If Pyongyang was not heeding the call to return to the talks, the patience of the other parties would run out.

'Everybody is aware there are other options in the international system,' she said, without elaboration.

North Korea yesterday announced it had increased its nuclear arsenal to help prevent a US attack following a threat to do so last week, South Korea's Yonhap news agency reported

Meanwhile, Dr Rice said China's rapid economic growth was being closely watched by the world. While growth was a good thing, the US hoped it would be 'encapsulated in a rule-based' global environment.

During her discussions with Chinese officials, the secretary of state raised human rights and religious-freedom issues. She also attended a religious service in a government-sanctioned Protestant church on Sunday.