Mr Higgins was accompanied by his wife Sabina Higgins to vote at a polling station in St Mary's Hospital in Dublin.

The president greeted the assembled count staff and press and said he was glad the weather had remained sunny, despite reports of a storm.

Voting is under way in Ireland in what is shaping up to be one of the most unpredictable elections in years.

If opinion polls prove correct, Sinn Fein is on course to challenge the 90-year duopoly of the state's two main parties, Fianna Fail and Fine Gael.

Taoiseach and Fine Gael leader Leo Varadkar is facing a difficult battle to hang on to power, with recent polls putting his party in third place.

In the last major survey of the electorate before polling day, Sinn Fein was leading the popularity stakes on 25 per cent, with Fianna Fail second on 23 per cent and Mr Varadkar's party on 20 per cent.

If those levels of support are borne out when the counting of votes begins on Sunday, it would herald a major breakthrough for Sinn Fein south of the border.

No party is expected to reach the 80-seat threshold to enable it to govern on its own, and a coalition administration of some complexion is almost inevitable.

Brexit did not feature prominently in a campaign that was instead dominated by domestic issues such as spiralling rental prices, record-breaking homeless numbers, controversy over the state pension age and a struggling health service.

There appears to be a mood for change and Sinn Fein could attract support from younger voters who want to end Fine Gael's nine years in power but are unwilling to trust Fianna Fail again after the financial crash that marked its last term of office.

Ireland could be in for more protracted government-formation talks if this election produces another fractured result.

Australian Associated Press