The chances of Britain leaving the EU have never been higher as bookies slashed the odds on a Brexit.
Ladbrokes odds on Britain making an exit after a referendum, expected to take place next year, were cut from 7/2 from 11/8 within the past three months.
The chances of Britain leaving Europe now stand at an all-time high of 40 per cent.
"The polls and the odds suggest this could be a photo-finish. The Prime Minister's negotiation efforts do not as yet appear to have impressed political punters," said Ladbrokes head of political odds Matthew Shaddick.
The bookmaker said the result is likely to close to call based on odds on how England votes, meanwhile, Scotland is favourite to vote in the same way they did in the Scottish independence referendum - in favour of staying together.