Mr Lew, a marketing consultant, alleged Mr Tsang misused the $50,000 he donated in 1997 to the Action Committee for Defending the Diaoyu Islands, of which Mr Tsang is a core member.

Mr Tsang said Mr Lew's claims were politically motivated. Mr Lew maintained he was telling the truth, prompting the lie-detector test, scheduled for last night.

A deal, struck on Thursday by both parties' lawyers and witnesses, said that if Mr Tsang passed the test, Mr Lew would donate $5 million to charity. If he failed, the Bull would not take part in unauthorised protests for 20 years.

Mr Lew was supposed to prepare a bank draft for $5 million by noon yesterday but demanded to amend the agreement minutes before the deadline, saying that otherwise he would not pay.

Mr Tsang said the test was then aborted on legal advice. 'Mr Lew breached the agreement. There is no point going ahead. He had wanted to evade the polygraph. The public can judge by themselves who has been untruthful,' Mr Tsang said, adding Mr Lew should publicly retract his allegations.

Mr Lew said he only wanted to amend the agreement slightly to make it fairer. He was part of the Alliance of Worldwide Chinese for the Protection of the Diaoyu Islands, formed by the pro-Beijing camp during the peak of the Diaoyu protests in 1996. Alliance activist David Chan Yuk-cheung drowned during one trip to the islands.

Former legislator Christine Loh Kung-wai refused yesterday to publicly apologise to the New Century Forum, which claimed that she had used a derogatory phrase to a forum member in a television show last month.

Ms Loh, the show's host, asked Law Cheung-kwok, a forum member who is standing in New Territories East, to respond to comments that his group was an 'opportunistic gathering'.

The forum said the phrase carried a negative meaning and demanded Ms Loh make a public apology. Ms Loh said: 'I don't know why they are so upset. I was only asking a question and wanted to see how he would answer it.'