People in the Irish Republic have voted in a referendum on whether to ratify the European Union reform treaty.

The BBC's Jonny Dymond in Dublin says all eyes are on the turnout, as a low figure would suggest a rejection which could plunge the EU into crisis.

Some reports suggest Thursday's voter turnout was about 40%. Results are expected later on Friday.

All 27 member states have to ratify the treaty for it to take effect, but only Ireland has held a public vote on it.

The treaty is aimed at streamlining decision-making in the EU to cope with its expansion into eastern Europe and would reduce countries' veto powers.

Turnout during the Irish vote was being watched intently across Europe

The Lisbon Treaty replaces a more ambitious draft constitution that was rejected by French and Dutch voters in 2005.

Turnout key

Opinion polls suggesting the referendum's result is too close to call, despite a high-profile "Yes" campaign led by Prime Minister Brian Cowen which had the support of most of the country's main parties.

Any turnout higher than 40% will bring a smile to the Yes campaign, our correspondent says.

The treaty provides for a streamlining of the European Commission, the removal of the national veto in more policy areas, a new president of the European Council and a strengthened foreign affairs post. Fourteen countries have completed ratification so far.

Irish polls closed at 2200 (2100 GMT) and counting starts on Friday morning, with the result expected soon after 1530 (1430 GMT).

RTE reported turnout was "brisk" in Kilkenny and Wicklow, but in many other areas, including Cork, Meath and Louth, it was slow.

Just over three million Irish voters are registered - in a European Union of 490 million people.

In 2001, Irish voters almost wrecked EU plans to expand eastwards when they rejected the Nice treaty. It was only passed in a much-criticised second vote.

This time the No campaign is a broad coalition ranging from lobby group Libertas to Sinn Fein, the only party in parliament to oppose the treaty.

Prime Minister Brian Cowen accused the No camp of "misrepresentation", saying voters had voiced concern about "issues that clearly weren't in the treaty at all", the Irish Times reported.

Declan Ganley of the anti-treaty group Libertas said he hoped a No vote would send "a clear message to Brussels" about democracy. "The voice of the Irish people is not to be questioned," he added.

Jose Manuel Barroso, President of the European Commission, urged all EU states to back the treaty, which is due to come into force on 1 January 2009.

He said the reforms would strengthen the EU to meet global challenges.

French Prime Minister Francois Fillon said a No vote in Ireland would spell the end of the treaty.

news.bbc.co.uk/2/hi/europe/7449313.stm