Irish politicians will spend a second day debating a controversial bill that would allow abortion where a woman’s life is at risk, delaying the historic vote on the issue.

The landmark law, which permits a woman to have an abortion if doctors agree she is suicidal, was expected to be introduced early this morning.

But opposition proved fierce and as debate continued through the night and passed the 5am deadline, forcing leaders to adjourn the Dail parliament with plans to re-start discussions this afternoon.

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The Protection of Life During Pregnancy Bill 2013 is popular with the majority of the country’s politicians, but some have been swayed by large pro-life demonstrations that continued across Ireland yesterday.

The added opposition of some powerful front and backbenchers have further delayed proceedings, including the much-anticipated rebellion of Lucinda Creighton, the Minister for European Affairs.

A small band of like-successful pro-choice campaign also amassed in Dublin last night, carrying imaged of Indian dentist Savita Halappanavar, whose death in an Irish hospital in October last year after being denied an abortion reignited the debate.

Her widower Praveen claimed the couple had been told a termination was not allowed because "Ireland is a Catholic country".

So fraught has debate around the legislation been that rebel members of Fine Gael, the senior coalition Government party, have been threatened with being barred from standing for the party at the next election.

Meanwhile, hate mail and death threats have been sent to politicians by pro-life protesters, and intimidation of campaigners has raged throughout the debate.

Taoiseach Enda Kenny has stood firm on his hard line, insisting his members are well aware of the consequences of breaking ranks.

"The rules of the Fine Gael party are not set by me," Mr Kenny said. "They are set by the supporters of the party at the Ard Fheis (annual conference) and those rules are very clear and everybody understands them."

Six pro-choice TDs are to vote against the legislation, claiming it does not go far enough to protect the lives of women. Richard Boyd Barrett, Clare Daly, Mick Wallace, Luke Ming Flanagan, Joe Higgins and Joan Collins have claimed the bill is unnecessarily restrictive and criticised the fact it seeks to criminalise women who have an unlawful abortion.

The legislation follows a 1992 judgment by the Supreme Court in Dublin, known as the X case, where judges ruled that abortion should be allowed if there was a threat to the mother's life, including suicide.

Ireland was also under pressure after a European Court of Human Rights ruling that a woman in remission with cancer was discriminated against because she was forced to travel overseas for a termination.

Additional reporting by PA