Fianna Fáil leader Micheál Martin has criticised the behaviour of Taoiseach Leo Varadkar during a debate with Sinn Féin deputy leader Mary Lou McDonald.

Mr Varadkar and Ms McDonald have been involved in fiery exchanges in the Dáil this week.

Speaking to reporters on Thursday, Mr Martin said Mr Varadkar should be conscious of the office he now holds.

He said: “Some of the exchanges were petty, too personal. Politicians should always focus on substance and policy and argue on that basis as opposed to petty, partisan engagements.”

During a debate on Wednesday, Mr Varadkar accused Ms McDonald of being very cranky during the sharp exchange, in which the Dublin Central TD accused him of being “facile and dismissive on important issues.’’

The exchange began after Ms McDonald accused the Government of failing to tax the banks.

The Taoiseach began his reply by sarcastically complimenting her “on a flawless delivery’’ of her script.

“Pauses, intonation, everything was absolutely perfect as always,’’ he added. “I hope she did not spend too much time practising this morning.’’