If any trouble occurs on the Taiwan question, it would be difficult for China-US relations to move forward

Chinese Vice-President Hu Jintao

In a speech to business leaders and academics, Mr Hu said that "properly handling the issue" was the key to promoting constructive ties between the two countries.

He had earlier met with President George Bush for talks covering China's human rights and the US-led war against terrorism.

China views Taiwan as a renegade province and is angry over US arms sales to Taiwan.

Analysts say Mr Hu - widely expected to be China's next president - adopted a firm but non-inflammatory tone on his speech on Wednesday night.

Warning

"If any trouble occurs on the Taiwan question, it would be difficult for China-US relations to move forward and retrogression may even occur," Mr Hu warned in his address in a hotel dining room in Washington.

Taiwan issue

1979 US switches diplomatic recognition from Taiwan to China 1979 Taiwan Relations Act says US will sell Taiwan defensive weapons 1998 President Clinton backs China's 'three nos' - no independence, no two Chinas, no Taiwanese statehood 2001 President Bush says US will do "whatever it takes" to defend Taiwan

He said selling sophisticated arms to Taiwan or "upgrading relations" with Taipei was "inconsistent" with US commitments to China under the US' "one-China policy", which disallows any links with Taiwan.

China has been rattled by President Bush's Taiwan policy. Previous administrations have been ambiguous about US support for Taiwan in the event of a Chinese attack, but President Bush vowed last year to do "whatever it took" to defend the island.

China was also incensed when Mr Bush agreed a large arms sale to Taiwan last year.

But despite the thorny issue of Taiwan, Mr Hu was upbeat over his 30-minute talk with President Bush - their first substantive meeting.

'Candid talks'

He told his audience that the talks were "candid and constructive", and said he was left with a strong feeling that despite different histories and differences on some issues, China and the US "are eager to see the relationship grow".

In a symbolic gesture Mr Hu visited the Pentagon

Mr Bush was reported to be similarly optimistic. White House spokesman Ari Fleischer said the US president "noted there may be some disagreements, but... believed they could be addressed productively".

During his visit Mr Hu has also held talks with Vice-President Dick Cheney, Secretary of State Colin Powell, Defence Secretary Donald Rumsfeld, and congressional leaders.

Mr Hu is widely expected to become China's Communist party leader in the autumn, and then take over the presidency when President Jiang Zemin retires next year.