The remarks by Labour minister Seán Sherlock come as the opposition threaten to bring a motion of no confidence in Mr Barrett over his claim that they are out to undermine him.

Mr Sherlock, minister of state for development and north-south co-operation, told the Irish Examiner last night: “My own view is that if there are question marks around this, then they need to be answered. In any parliamentary democracy, any need for debate needs to be paramount.”

Mr Barrett faces questions over why he stopped last week’s debate over the terms for the inquiry and what exact advice he received in deciding this.

He says he decided for legal reasons to stop the debate after he was contacted by lawyers for Alan Shatter, the former justice minister.

Mr Shatter has launched a High Court action to overturn the Guerin report, which originally led to his resignation, as well as the aforementioned inquiry being set up.

Pat Rabbitte, former minister for communications, yesterday said he had “serious reservations” about the legal advice the Ceann Comhairle had received.

Mr Sherlock said these reservations needed further consideration. “If there is need for debate, then let’s have it,” he said. “There is no line drawn under this matter at the moment.”

However, the row took another turn after Mr Barrett, as Dáil chairman, went on radio last week and defended his actions and impartiality. He also told RTÉ that the opposition were trying to “get” him.

There is now growing concern in Government circles that the opposition parties will unite and force a motion of no confidence in Mr Barrett.

Fianna Fáil is threatening to withdraw support in the Dáil, Sinn Féin has openly suggested a motion, and independents meet Mr Barrett this week over concerns about their Dáil speaking slots. Fianna Fáil also contends there is precedent in its claim that the Dáil did not need to be “silenced” last week.

Mr Barrett was abroad last night, but sources close to him said that his position was unchanged. A spokesman for Tánaiste and Labour leader Joan Burton said her position remained unchanged from last week when she said she was “surprised” the Dáil debate on the inquiry did not go ahead.

The inquiry is set to examine alleged Garda mishandling of investigations in Cavan and Monaghan.