The Tánaiste has defended the Government's decision to hold the referendum restricting the citizenship rights of children of foreign nationals.Amid heated exchanges with Opposition deputies, Ms Harney said the referendum provided for some of the most liberal laws on citizenship anywhere in Europe.

"It is important and timely that we plug the loophole in the law on citizenship as quickly as possible. It is better to do that on June 11th rather than wait for a presidential election, which may or may not occur later this year."

She said the Government had only made the decision on Tuesday after a great deal of consultation and discussion.

"I strongly resent any suggestion that it was known a week or two weeks ago."

Ms Harney said that at a meeting between the Minister for Justice, Mr McDowell, the masters of maternity hospitals had said that "if what is happening in Dublin continues, with 22 per cent of births being to non-nationals, we will quickly need another maternity hospital."

Mr Gay Mitchell (FG, Dublin South Central) was ordered from the House when he sought to make a point of order about a question he had tabled some weeks ago on the number of immigrant children being born.

The Ceann Comhairle, Dr Rory O'Hanlon, said it was not valid at leaders' question time.

Earlier, the Fine Gael leader, Mr Enda Kenny, asked why the Government was pressing ahead with the referendum on that date.

"Is it not obvious from past experience of previous governments that rushing to amend the Constitution can lead to legal quagmires and that what the Government is doing, by forcing this through on June 11th, is debasing Bunreacht na hÉireann and dragging it down to the level of party political gain when it is facing an electoral process with difficulties on all fronts?"

He added that he recognised there was a problem and his party was committed to a resolution of it in a constructive, coherent and all-embracing manner ... Why had the Taoiseach, Mr Ahern, not referred to the referendum when he answered questions on the issue on February 17th?

Ms Harney said the Government was usually criticised by the Opposition for not acting in a hasty fashion on many matters.

Asked by Mr Brendan Howlin (Labour, Wexford) if she had consulted the PDs, Ms Harney replied: "I am more than happy to talk to the Progressive Democrats, and I will take no lectures from Deputy Howlin or anybody else in this matter."

The Labour leader, Mr Pat Rabbitte, said that despite their political differences he had always regarded the Tanaiste as a decent person in politics and an honourable colleague in the constituency.

"It makes my stomach sick to see her lend her party as cover to Fianna Fáil in a transparent ploy to exploit the immigration issue in an election atmosphere." The handling of the matter, he added, had been "dishonest and underhand right from the beginning, on February 17th, when the Taoiseach said there would be no referendum this year, up to the battle Deputy Higgins and I fought yesterday to extract from the Taoiseach, against obfuscation and obstruction, including from the Chair, the statement that there would be a referendum on June 11th."

The Government, said Mr Rabbitte, intended to release the Bill "under the cover of a holiday weekend", adding that he wondered where was Mr Des O'Malley when he had stood by the Republic. ". The Minister for Justice, Mr McDowell, he said, was drunk with power, prepared to do anything to keep his feet under the Cabinet table.

Ms Harney said she regretted that Mr Rabbitte intended having the debate starting on that note. She said some people had exploited the issue in the last election, adding: "It behoves us all to conduct the debate, even from this moment, in a fair and calm fashion."