He was referring to a pre-election vow made by Mr Chen during his re-election campaign that he would push for a referendum in 2006 to create a new constitution and adopt it by 2008.

But in taking his oath as president for a second, four-year term on May 20, Mr Chen backpedalled on his previous pledge by saying he would no longer push for a new constitution.

Instead, he would pursue a constitutional amendment that would not touch on sovereignty or sensitive political issues.

Beijing has repeatedly said Mr Chen's constitutional plan is actually a pro-independence agenda that he will push during his new term - an agenda that would make war inevitable.

Mr Wang was quoted as saying in the interview that Mr Chen 'has not substantially changed his separatist scheme, although he used the term 'constitutional re-engineering' in his May 20 inauguration speech to cover up his plot to promote formal independence'.

'We cannot completely rule out the possibility [of a military conflict] though it is not at all what we hope for,' he said.

'There will be no way for us to break the ice in political ties in the coming four years unless Chen returns to the one-China principle.'

Mr Wang said what Beijing would do was 'just work hard to prevent bilateral relations from deteriorating'.

He also said it would be an unwise move for Taiwan to buy more advanced weapons from the US.

Observers said Mr Wang's comments reflected the mainland's suspicion of the Taiwanese president's stance.

They said Mr Chen's poor credibility record and his frequent U-turns on policies were the major reasons Beijing had found him untrustworthy. In Taiwan, Chiu Tai-san, spokesman and vice-chairman of the Mainland Affairs Council, said Mr Chen had already made it clear he would not push for a new constitution, and it would be unfair for the mainland to continue to accuse the president of pursuing this.

Speaking at the opening of a workshop in Taipei, Mr Chen yesterday also reaffirmed his commitment to upholding his basic concepts, principals and promises concerning cross-strait relations in his second term.

'In the next four years, I will stand by what I have pronounced in the cross-strait policy, which is aimed to promote peaceful development between the two sides of the Taiwan Strait,' he said.

But on the previous night, Mr Chen lashed out at a recent suggestion by Mr Wang that the mainland might adopt a law requiring Taiwan to reunify with the mainland.

'The Chinese communists want to undertake a legal battle to turn Taiwan into a special political zone. If Taiwan does not follow, it then has the excuse to launch a military attack of Taiwan,' he said during a visit to southern Taiwan on Thursday.