Ireland's Prime Minister has hailed a "historic moment" for women in the country, after a bill to legalize abortion passed through the final stages of parliament.

The bill is now set to be signed into law by President Michael D. Higgins, following a marathon debate in parliament's upper house Thursday, and will come into force in January.

Two-thirds of Irish voters agreed to amend the constitution and allow women to access abortion in a momentous and emotionally charged referendum in May.

Prime Minister Leo Varadkar thanked the bill's supporters on Twitter and commended Health Minister Simon Harris for steering it through parliament. The bill passed through parliament's lower house, the Dáil, last week.

The vote would "end lonely journeys, end the stigma and support women's choices in our own country," Harris said on Twitter Thursday.

But its passage also prompted vandals to target a regional office of Ireland's governing party Fine Gael overnight, writing "baby killers" and "Herods" on its wall.

"I was so disappointed to see this morning (Friday) that my busy constituency office in Sligo has been vandalized and defaced overnight," Tony McLoughlin, the assistant government whip, wrote on Twitter.

"We live in a proud democracy and despite anyone's opinion on any referendum, this behavior can never be condoned," he added.

The new laws make abortion legal and unrestricted in the first 12 weeks of pregnancy, subject to a medical consultation and a cooling-off period. Terminations after 12 weeks would be permitted only under exceptional circumstances.

After the vote, Harris paid tribute to "the campaigners who fought for 35 years to change a nation, to change hearts and minds," the UK Press Association reported. "I want to thank the minority who fought the battle in here when it was convenient for the majority to ignore."

"But today, I think mostly of the thousands of women who were forced to make the journey to access care that should have been available in their own country," he added.

Around 3,000 Irish women annually have traveled to Britain to terminate a pregnancy in recent years, according to UK government figures.