Betting odds on a British vote to exit the European Union narrowed today after an opinion poll gave the "Leave" camp a double-digit lead over "Remain."

The implied probability of a vote to stay in the EU in a June 23 referendum fell to 70 per cent from 78 per cent earlier this week, according to odds supplied by bookmaker Betfair.

It was responding to the publication of an opinion poll by ORB for The Independent newspaper on Friday showing support for "Leave" on 55 percent, versus 45 percent for "Remain".

Financial markets have been paying close attention to bookmakers' odds on the referendum, especially as opinion pollsters suffered a blow to their credibility when they failed to predict last year's outright election victory for Prime Minster David Cameron's Conservatives.

Yesterday's survey showed the biggest lead enjoyed by the so-called Brexit camp since the poll series started a year ago

Yesterday's survey showed the biggest lead enjoyed by the so-called Brexit camp since the poll series started a year ago, The Independent said. But the official Vote Leave campaign reacted cautiously, saying on Twitter: "We don't believe the ORB online poll, our data suggests it's closer to 50-50."

Bookmaker Ladbrokes said the ORB poll had caused it to shorten its Brexit odds to 9/4 from 11/4 previously.

"We thought the Brexit rally was finished but the leave odds have tumbled again on the back of the eye-catching 10 point poll," said a Ladbrokes spokesman.

Asked about the contradiction between the betting odds and the poll, he said the former reflected the weight of money in the market.

"Since we first started taking bets on this, 80 percent of the money we've taken has been for 'Remain'. This is like any other market, the money moves the market," the spokesman said.

"Polling is a snapshot of voter intention at any given point; a betting market is a predictions market."

Britain's decision on whether to leave the world's largest free-trading area carries far-reaching implications for politics, the economy, trade, defence and migration in Britain and the rest of the EU.

The mixed picture from bookmakers and pollsters has heightened market jitters about the outcome, with sterling repeatedly reacting to poll results. The pound lost more than half a cent against the dollar soon after the ORB poll was released.

Separately on Saturday, a group of Britain's most eminent scientists endorsed the campaign for the UK to remain in the EU, saying that leaving could damage research.

On Friday, however, billionaire entrepreneur James Dyson came out in favour of Brexit, a significant endorsement for the "Leave" camp with less than two weeks to go before the vote.

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