In an interview with Taiwan-based SET TV cable news broadcast on Monday, Mr Chen accused Mr Soong of striking a bargain with the State Council's Taiwan Affairs Office director, Chen Yunlin , in the US earlier this year.

The president claimed Mr Soong reached a deal with the mainland official to vote against the constitutional amendments to be debated by the National Assembly at the end of this month in exchange for the mainland's permission for his visit.

President Chen also revealed that to reach a 10-point consensus in late February on cross-strait and political parties' reconciliation, Mr Soong agreed to support his government on key bills, including the US arms procurement budget, after he returned from the mainland.

Taiwanese media reports yesterday said Mr Soong flatly denied Mr Chen's claims.

'Before I came to the mainland, I had never met Chen Yunlin, and during my stay in the US, I must clearly say that I had not met any Chinese communist cadres nor any Chinese communist members,' he told Taiwanese reporters accompanying him.

Mr Soong also denied that he had made any deal with Mr Chen.

Taiwanese media said Mr Chen was facing strong pressure from pro-independence supporters who were angry with his policy U-turn by co-operating with Mr Soong and approving the opposition leaders' visits.

In Taipei, angry PFP lawmakers yesterday demanded an apology from Mr Chen, saying his comments had tarnished Mr Soong's reputation.

PFP secretary-general Chin Chin-sheng said Mr Chen's aide, Yu Shyi-kun, called him on Monday night to explain the president's actions.

Report said Mr Yu told Mr Chin the president was under pressure from pro-independence hardliners and had to make the comments to pacify them.

But the Presidential Office said Mr Yu told Mr Chin the president did not directly attack Mr Soong. 'He [Chen] was only commenting on certain incidents, not against any individual,' the office said.

Equally furious were officials of the pro-independence Taiwan Solidarity Union (TSU), a former ally of Mr Chen's ruling Democratic Progressive Party.

In his interview, Mr Chen lashed out at former president Lee Teng-hui, now spiritual leader of the TSU and pro-independence fundamentalists, for making irresponsible and unreasonable demands over changing the island's status and constitution.

The TSU also cried foul yesterday over Mr Lee being shut out from a television interview where he was due to make a rebuttal of Mr Chen's claims.

'Originally the former president was to give an exclusive interview with Era TV today, but late last night, the producer called to say they were pressured and could not give Mr Lee the television time,' TSU secretary-general Chen Chien-min said.

Some DPP members labelled Mr Chen's attack as improper, saying it would create more problems.

'He [Mr Chen] criticised everybody during his interview,' former DPP legislator Shen Fu-hsiung said. 'This only revealed his weakness, proving that he is unable to run the country.'

DPP legislator Lin Cho-shui said Mr Chen had only inflamed tensions with his actions.