Cheng will team up with The Frontier's Andrew To Kwan-hang, who will rank second on the list. Mr To could not be reached for comment last night.

Some democrats are hoping Cheng will help their camp knock out pro-government candidate Chan Kam-lam, of the Democratic Alliance for Betterment of Hong Kong, and win three or even four of the five seats up for grabs.

Cheng yesterday filed a complaint to the Independent Commission Against Corruption alleging Commercial Radio tried to block him standing in the election. He will also make a complaint to the Election Affairs Commission today.

However, when he spoke on RTHK yesterday he offered a different interpretation of a letter central to his dispute with Commercial Radio over his removal from the popular Teacup in a Storm show.

When he spoke about the letter on Monday he said that Commercial Radio would only pay him the remainder of his contract if he did not run in the election. But he claimed on RTHK that Commercial Radio said it would not pay him if he stands.

He also spoke for the first time about the reasons behind his departure from the airwaves earlier this year. He supported media speculation that he had left because a person with a triad background had talked to him twice - last November and March - asking him to stop criticising the government.

'He didn't mention money or quitting the show. He talked about consequences,' Cheng said.

'He asked me to stop criticising the Hong Kong government.

'He represents a mainland organisation, an official, a leader.

'He passed the words to me. He also said they were prepared to do anything.'

Cheng said the middleman had also talked to fellow radio host Wong Yuk-man, who also left the station citing intimidation.

'Wong Yuk-man had been beaten,' Cheng said.

'His restaurant was splashed with red paint; then he was beaten. My company was splashed with red paint.

' I don't want to be beaten.'

The ICAC yesterday declined to comment on Cheng's complaint, saying it normally contacted a complainant within 48 hours to arrange an interview.

Cheng said he decided to stand in Kowloon East because fellow democrats consider he would contribute more there.

'Now we should be able to win three seats at least, possibly four and oust Chan Kam-lam,' he said.

Barrister candidate Alan Leong Kah-kit said it was a good move for Cheng to join the fray in Kowloon East, but he would not be drawn on whether he would take votes away from him.

Democrat Fred Li Wah-ming, who is leading a three-way ticket in the constituency, said he would continue with his own campaign.

Cheng said consultant Leung Man-to, who has been asked to stop filling in as host of Teacup in a Storm, had agreed to help him campaign.

It is understood that Wong will also help when he returns from overseas.