The Labour leader says he would not have had confidence in the former Garda Commissioner, if he knew he was looking to undermine Maurice McCabe.

Brendan Howlin says he is troubled by claims that Martin Callinan secretly met with TD John McGuinness in the run-up to the whistleblower’s appearance at the Public Accounts Committee.

The former minister repeatedly stated his confidence in Mr Callinan at the time.

However, Mr Howlin says his opinion would have been different had he known of any secret meetings designed to undermine the whistleblower.

The leader of the Labour Party said: “The notion that somebody would seek to have a private meeting, and particularly one in a car park, to – as is alleged by John McGuinness – undermine the bona fides and character of a crucial witness is profoundly worrying.”