The former Garda Commissioner Martin Callinan is facing growing calls to confirm or deny allegations - he tried to discredit the Garda whistle-blower Maurice McCabe in a secret meeting with Fianna Fáil TD John McGuinness.

Last night, the Garda Commissioner Nóirín O'Sullivan denied any knowledge of a private meeting between her predecessor and the former chair of the Public Accounts Committee.

The Commissioner said she wanted to make sure whistle-blowers are welcomed and protected by Gardaí.

The controversy's likely to be raised in the Dáil this afternoon.

Sinn Féin's Mary Lou McDonald says it's time for Martin Callinan to give his version of events: