Ireland looks set to legalise abortion after an exit poll showed a referendum to remove the constitutional 8th emendment passing by an overwhelming 68% Yes to 32% No.

The move was backed by the leaders of all the major political parties, however the predicted margin of victory is larger than had been expected.

According to the Irish Times exit poll, 77% of the public in Dublin voted Yes, followed by 66% in Munster and 59% in Connacht. There was huge support among young voters, predicted to be 87% in the 18-24 age group, as well as expectations of a majority in all age groups under 65.

No doubt if results are confirmed it will be a seismic change in Irish attitudes to abortion over the past 35 years.

A surge in support had been seen in the last two weeks of the campaign, particularly among young people and via social media.

Counting of votes begins in two hours time (at 9am Irish time) with an official result expected to be declared in the afternoon.

Turnout is expected to be even higher than the previous referendum on same-sex marriage in 2015, which passed by 62% to 38% on a turnout of 60%.

Speaking at the close of polls, Sinn Fein's Mary Lou McDonald thanked party members from across Ireland and all those who campaigned for a Yes vote.

"The campaign created a space for Ireland, North and South, to look at the experiences of women and I believe that we are all better for that," she said.

"The voices of these women have been heard and can no longer be silenced by guilt or neglected by government", she added.