Varadkar admits he has voted for colleagues who were in chamber

A spokesman for Mr Varadkar said: "The Taoiseach has never asked anyone to vote on his behalf and has never voted on behalf of someone who was not in the chamber.

"On a small number of occasions he has cast a vote for a colleague but only ever if they were present in the chamber, as in 'present and voting' as the constitution requires."

The spokesman also pointed to remarks made by Mr Varadkar in the Dáil today.

The Taoiseach told the Dáil: "There is a world of difference between someone being present in the chamber, although not in one's seat, and not being present in the chamber or the building at all.

"To allay any future concerns or confusion, all members should be in their seats for all votes from now on."

Fianna Fáil leader Micheál Martin, meanwhile, admitted he had cast Dáil votes on behalf of other TDs, but also insisted they were in the chamber at the time. It also emerged his vote was recorded while he was apparently not in the chamber.

During a Dáil debate on reducing the number of seats in the EU Parliament in February, Mr Martin is recorded as not being present for two of the three votes on the legislation. However, for the final vote the Fianna Fáil leader's vote is recorded as being present. During the debate, Fianna Fáil housing spokesperson Darragh O'Brien was sitting in Mr Martin seat as he was taking the legislation for the party.

For the first two votes, Mr O'Brien is recorded as voting in his own seat despite sitting in the party leader's seat.

However, for the third and final vote, Mr O'Brien is not recorded as voting in his own seat. Mr O'Brien last night admitted he may have incorrectly pressed Mr Martin's voting button at the end of the debate.

Mr Martin, whose party has been thrown into chaos by the 'phantom votes' controversy, said the practice of TDs pressing the voting buttons of their colleagues "should come to an end".

The 'Votegate' storm erupted after it was revealed that Fianna Fáil TD Timmy Dooley's vote was recorded on six occasions during a Dáil session despite his absence from the chamber.

The revelations have also exposed an apparently common practice of TDs pressing other Dáil members' voting buttons when they are elsewhere in the chamber.

The main party leaders have all said this practice should end. Sinn Féin's Mary Lou McDonald, Labour leader Brendan Howlin, Eamon Ryan of the Green Party, and Social Democrats co-leaders Catherine Murphy and Róisín Shortall said they have never pressed another TD's voting button and never asked another TD to vote on their behalf.