Ireland was voting in a general election on Saturday with the prospect of left-wing republican party Sinn Fein beating the country's two main political forces for the first time.

‘The choice is clear: Go with Fine Gael ... or hand our country back to those who wrecked it,’ outgoing Prime Minister Leo Varadkar and centre-right Fine Gael party leader tweeted on Friday.

Fine Gael's traditional rival Fianna Fail was the main party in government when Ireland experienced an economic collapse over a decade ago.

In addition, a vote for Sinn Fein would be ‘risking everything,’ not just the economy but also the ‘democratic institutions’ of the state, Varadkar said at Fine Gael's final press conference on Thursday.

Opinion polls suggest that Fine Gael failed to sell its message of economic recovery, with Sinn Fein - once viewed as the political wing of the terrorist Irish Republican Army (IRA) - edging ahead of both the centre-right Fine Gael and Fianna Fail parties.

However, Sinn Fein leader Mary Lou McDonald's handling of the fallout from the brutal murder of a young man in 2007, allegedly by the IRA, has raised questions about her leadership.

The mother of the victim urged voters to shun Sinn Fein after one of its leading members said her son was involved in criminality.

Although unemployment is down to 4.5 per cent and 2020 growth is forecast to hit 3.3 per cent, homelessness and the health service dominated the election campaign.

Sinn Fein has promised a rent freeze and 100,000 new social houses if elected. Fianna Fail has pledged to build 200,000 new homes by 2025 and an end to long-term homelessness.

Fine Gael led a minority government supported by a confidence-and-supply agreement with the opposition Fianna Fail for the last four years.

Fianna Fail, marginally ahead of Fine Gael in opinion polls, has ruled out entering such an agreement again.

Both parties have vowed not to form a coalition with Sinn Fein.

Ireland hopes to boost turnout by holding its first election on a Saturday.

Some 3.1 million voters are eligible to elect 160 members to the 33rd Dail.

Polling stations open from 7 am (0700 GMT) to 10 pm in 39 constituencies.