The Cabinet has approved the main points of the legislation on abortion that will be brought forward if the referendum on the Eighth Amendment is passed.

Minister for Health Simon Harris said it proposes to make terminations lawful where an appropriate medical practitioner has certified that pregnancy has not exceeded 12 weeks.

Some 72 hours must elapse between the certification and the termination being carried out.

Mr Harris said that beyond the first 12 weeks, terminations would only be available in exceptional circumstances.

These include where there is a risk of serious harm to the health or life of the woman, in emergency situations and in cases of fatal foetal abnormality.

He said in all other circumstances abortion would remain unlawful.

The Minister said in cases where there was a risk to the life or health of a woman, termination would not be lawful "beyond viability."

"The viability of the foetus would be assessed and agreed by two doctors... if viability is established and the pregnancy is ended on health grounds, then it will be done through early delivery with a full medical team."

Speaking at Government Buildings, Mr Harris said that the date for the referendum on the Eight Amendment will be set this week. 

The bill to allow a referendum on the Eighth Amendment being held has passed second stage in the Seanad tonight.

After almost five hours of debate, the bill was passed by 35 votes in favour to ten votes against.

The debate has now adjourned for the night and it will resume for the remaining stages tomorrow.

Earlier, the Seanad heard Fine Gael Senator Maura Hopkins say that she would not be supporting the proposal to allow for unrestricted abortions up to 12 weeks.

She told the Seanad: "I do support access to options in certain circumstances; however I cannot support abortion without any restriction up to three months.

"I do believe that women receive the necessary care and support in very difficult circumstances, however, I also believe that we have a responsibility to protect the rights of the unborn child."

"I believe it is important that people know my view. This is my personal view, and I do not wish in any way wish to influence the views of others.

Ms Hopkins added: "I will be supporting the Government's decision to hold a referendum later this year on the matter in order to allow the Irish people have their say."

Two-thirds majority requirement proposal rejected

Earlier, a proposal by Tánaiste Simon Coveney to ensure that legislation on abortion could not be changed without a two-thirds Dáil majority was rejected.

Mr Coveney believed that such a measure would counter claims that politicians could not be trusted on the issue.

"To put that into context, that is more than the combined strength of Fine Gael and Fianna Fáil in the current Dáil," a spokesperson for Mr Coveney said.

Earlier, Taoiseach Leo Varadkar said that the Attorney General believed the idea was unconstitutional.

Mr Varadkar said that it would not form part of the general scheme of the legislation, which is to be published later tonight.

This afternoon, a spokesperson for Mr Coveney said the heads of the proposed bill on abortion will show the detail and assurances that the Tánaiste has sought and consulted with the Minister for Health on for many weeks.

The option of a legislative lock was discussed earlier today, but they said this would require constitutional change and is not possible in the time frame.

"It in no way alters the Tánaiste's full support for the heads being brought forward by Minister Harris," the spokesperson said.

The proposal was criticised by opposition politicians.

Solidarity-PBP TD Bríd Smith described the idea as anti-democratic and outrageous, while Independent TD Mattie McGrath accused the Tánaiste of taking a wrecking ball to the Constitution.

He said the Government is engaging in legal gymnastics on this issue.

The proposal by the Tánaiste was also described by Labour leader Brendan Howlin as unconstitutional.

Social Democrats TD Catherine Murphy said the Tánaiste's proposal was not constitutional and it created confusion.

She said all legislation in the Dáil requires a simple majority and to change that would require a change to the Constitution.

Sinn Féin said Mr Coveney's idea was very likely to be unconstitutional but the party would wait to see the draft legislation before making a final judgement.

Fianna Fáil Spokesperson on Education Thomas Byrne said he does not know what Mr Coveney's agenda was in proposing a two thirds majority in the Dail to pass the legislation.

He said he had no issue with the Tánaiste changing his mind and backing a proposal for abortion up to 12 weeks, but said for him to moot proposals that are impossible is subject to criticism.

Additional reporting Martina Fitzgerald, Colman O'Sullivan and Conor McMorrow