Former Justice Minister Alan Shatter will appear on the Late Late Show tonight, where he is expected to discuss his resignation.

Reports suggest Alan Shatter will also go into detail about the Garda whistleblower controversy, as well as the Garda Ombudsman Commission.

Last week Shatter criticised GSOC and called for the head of the watchdog to step down.

Special Correspondent with the Irish Examiner, Mick Clifford, says tonight's interview could see Shatter lift the lid on the resignation of Commissioner Callinan.

"If it turns out that Mr [Enda] Kenny effectively sent Mr [Justice Department Secretary General Brian] Purcell out with that metaphorical revolver and bottle of whiskey to get Mr Callinan to do the decent thing or face the sack, then he was acting outside the law and Mr Kenny has a very serious problem," he said.

"Alan Shatter is one of the few people who may be able to fill us in on exactly what happened that night."