A UK move to leave the EU would be 'irreversible,' French President Francois Hollande said ahead of the vote. Separately, EU Commission chief Jean-Claude Juncker said there would be no new deals on the UK's status.
"Out is out," the President of the European Commission, Jean-Claude Juncker, told reporters in Brussels on Wednesday, commenting on Thursday's UK referendum on staying in or leaving the European Union (EU).
The European bloc would not offer new terms for cooperating with Britain, regardless of the outcome, Juncker added. "The British policy makers and British voters have to know that there will not be any kind of renegotiation," Juncker said.
His comments followed a statement by British Prime Minister David Cameron, who suggested he might push for more reforms if the UK voted to stay in the EU.
Juncker, however, said that the EU did not intend to go beyond the already existing deal Cameron and European leaders made in February.
"We have concluded a deal with the prime minister. He got the maximum he could receive; we gave the maximum we could give," the EU official said after meeting Austrian Chancellor Christian Kern.
'Extremely serious consequences'
France's President Hollande said that the referendum vote in the UK put the EU's future at stake.
"If the choice is to leave the EU ... that would be irreversible," Hollande said in Paris on Wednesday.
"There would be a very serious risk for Britain to lose its access to the single market and everything that goes with the European economic area. Everyone needs to be well aware of this," he said, warning of "extremely serious consequences."
Hollande said he would travel to Berlin next week: "Whatever happens, I will be in Germany next week to work... towards relaunching the European project," he told a joint news conference with Swedish Prime Minister Stefan Lofven.
Opinion polls and betting odds
Opinion polls are predicting a close result in the referendum on Thursday. However, pollsters failed to predict the outcome of the last general election and there is doubt over the accuracy of their projections.
John Curtice, the Strathclyde University professor who oversaw last year's accurate election exit poll, told the Daily Telegraph newspaper on Wednesday: "Some of the polls are definitely wrong."
Bookmaker odds still favor a 'remain' result. They have made the Remain camp the odds-on favorite since February.
Over the last week, bookmakers have shortened their odds dramatically, going from 4-6 (implying a 60 percent chance of winning), to as much 2-9 with an 82 percent chance of victory. In the past ten days opinion polls have swayed between a 10-point Brexit lead and a narrow two-point margin in favor of Remain.
There is no formal exit poll for the referendum although YouGov will poll on the day and release the numbers when voting ends at 10 p.m. local time (21.00 UTC). The first results are expected in the early hours of Friday morning, by about 3.30 am local time (02.30 UTC).
dj/jm (dpa, AFP, Reuters)