The anti-graft agency is seeking a High Court order for two media outlets to hand over records of interviews with Lew Mon-hung, a one-time supporter of Chief Executive Leung Chun-ying.
The Journalists Association slammed the request for journalistic materials from radio station Hong Kong Commercial Broadcasting and magazine publisher iSun Affairs, calling it a threat to press freedom.
Lew, a staunch supporter in Leung's election campaign, accused Leung, in an iSun interview published on January 24, of lying over his handling of illegal structures at homes on The Peak and of considering pan-democrats "enemies".
He also said Leung broke his promise to appoint him to the Executive Council or recommend him for membership of the Chinese People's Political Consultative Conference Standing Committee, as a reward for his support during the election.
According to court filings, the commissioner of the Independent Commission Against Corruption wants iSun to produce "notes, records and/or recording" linked to Lew's interview.
It also asks for "the original and unedited sound recordings" of telephone interviews with Lew aired on the radio show, On a Clear Day, on January 24 and 25.
Both media outlets said they had received ICAC requests for the materials, but did not comply because of journalistic ethics and customary practice.
Lew said he had not been asked by the graft-buster for such records.
"I do not know why the ICAC took the action. I do not know what it is checking," he said.
The ICAC made the court applications based on the Interpretation and General Clauses Ordinance. The law states that a judge may issue such an order if he is satisfied the material is likely to be of substantial value to the investigation of an arrestable offence where there are reasonable grounds for believing an offence has been committed. Alternatively, the judge must be satisfied that the material is likely to be relevant evidence in proceedings for the arrestable offence.
Failure to comply with the order without reasonable cause can warrant up to a year in jail and a HK$100,000 fine.
The Journalists Association said the ICAC move would harm public confidence in journalists, leading to a perception newsmen would not protect their sources.
The ICAC said it respected press freedom, but it might need to obtain materials required for investigation through legal proceedings if necessary. It made the application after seeking advice from the Department of Justice.