A senior Vatican official has told Irish politicians they should resign rather than vote for abortion, Msgr Jacques Suaudeau, scientific director of the Pontifical Academy for Life at the Vatican, told the Irish Catholic newspaper.

“If you are faithful to your conviction, then you have to get out,” he said.

He warned Catholic politicians to quit rather than vote for the abortion bill, “If a politician is being forced to be a formal co-operator with abortion, you leave the party, you get out.”

He said the Nuremberg Defence, a reference to Nazi officers who said they were simply following orders, is not good enough. “If an act is evil and you receive an order to do it then you cannot do it.

“Sometimes people forget Nuremberg. You cannot cover yourself with the cover of party discipline,” Msgr Suaudeau said.

“Generally, if you are well-known and your party is proposing something that goes against your conscience you need to make it known, you need to speak. Maybe they will ask you to abstain, sometimes people understand that you have an objection of conscience," he added.

He said  that, “Catholic politicians cannot live under two houses when it comes to abortion. You have to take a decision but not many do."

Prime Minister Enda Kenny reacted angrily to the charge, “I’m a Catholic and I don’t interfere in the messages of the church. I have no comment to make on what the cardinal from the Vatican says,” Mr Kenny said.

“I set out very clearly what it is we have to do in terms of our constitution and the law, and that’s to provide clarity and decisiveness. This is about saving lives, not ending them.”

Fianna Fail leader Micheal Martin announced that his party would have a free vote on the issue despite his best efforts to have the party support a position of approving the abortion bill. The bill is being introduced to comply with an Irish Supreme Court verdict allowing abortion when the life of the mother is in danger.