Speaking at Leaders’ Questions, Fianna Fáil leader Micheál Martin raised how Mr Varadkar had communicated with him in recent weeks about the unit’s establishment.
The Taoiseach insisted while it will have a budget of €5m, it will be “cost neutral” as it will be met within existing resources of his own department.
Mr Martin probed as to how John Concannon came to head up the unit and it emerged Mr Varadkar approached him about the position. However, Mr Varadkar insisted Mr Concannon was appointed by the secretary general in the department and not by him.
In a slip of the tongue, Mr Varadkar said: “I discussed it with the secretary general obviously before I appointed him as… or before I… or before I asked if he would be available to be appointed.”
Mr Martin attacked Mr Varadkar saying: “You appointed him, this was entirely political.”
Mr Martin asked why Mr Concannon and deputy director Andrea Pappin were not appointed through rules governing special advisers, used when an established civil servant is appointed to a role by a member of Government.
Mr Martin said “the appointment of the head in itself was a political act by you, Taoiseach. We understand your obsessions with communications but in essence, there are important issues about the politicisation of the civil service which must be avoided at all costs.”
The Taoiseach also denied he suppressed a Brexit report on implications for the Border in tetchy exchanges with Mr Martin.
Mr Martin claimed that it was “bad faith” on the part of the Taoiseach and the Government not to share the report drawn up by the Revenue Commissioners.
The Taoiseach replied: “Is Fianna Fáil, the republican party, arguing now we should start training up border guards, getting dogs ready, checking out sights for border posts and truck stops?”
Mr Varadkar said Mr Martin’s outrage did not seem genuine to him, given that everybody knew of the consequences of a hard border for Ireland.