Cheng told the South China Morning Post yesterday his contract with the station would not end until February 29, 2008.

Commercial Radio said Cheng was on leave until the end of September, but would not comment further.

Chinese-language newspapers reported yesterday that Commercial Radio, which has said repeatedly in the past two months that it would stand firm on protecting freedom of speech, planned to end Cheng's contract.

Sources were quoted as saying the management was unhappy with Cheng's unilateral decision to take leave.

He admitted he had talked to station managers yesterday and the question of when he would return to work was discussed. He declined to confirm whether his possible dismissal was discussed.

'They can of course fire me, if they give me the compensation required by my contract,' he said.

Cheng, an outspoken critic of the rich, the powerful and Beijing, returned to the show despite almost losing his life in a brutal chopping attack in 1998.

But the political pressure became too great for him and in May he announced he was leaving the show for an unspecified period.

His departure was followed swiftly by that of stand-in Allen Lee Peng-fei, who said he felt intimidated by a call from an unidentified former mainland official asking about his 'virtuous wife' and 'beautiful daughter'.

Mr Lee later also resigned as a deputy to the National People's Congress.

Their departures and that of fellow host Wong Yuk-man prompted a political storm and stirred fears of back door censorship by Beijing of outspoken pro-democracy figures.

A close friend of Cheng's said it seemed there had been a dispute with Commercial Radio but it was likely to have been contractual rather than political. 'It is really strange for them to think they should sack Tai Pan,' the friend said, using Cheng's nickname.

A politician close to Cheng said the issue was 'very suspicious' and urged the station to clear up the matter.