The Garda Commissioner Martin Callinan has resigned.

The commissioner handed his resignation to the Minister for Justice this morning, meaning it takes immediate effect.

He had originally been due to retire last August, when he turned 60 - but Minister Shatter had extended his term until August 2015.

Mr Callinan's position had been called into serious question after a number of ministers called on him to withdraw his description of the actions of the two Garda whistleblowers as 'disgusting'.

Although he retained the public support of the Taoiseach and Minister for Justice, a majority of the cabinet had called for action.

Our political correspondent Gavan Reilly reports: