LONDON (Reuters) - Three latest polls showed voters were still closely divided over whether to end Britain's European Union membership less than two weeks before the referendum.
The pound weakened by as much as 1.2 per cent against the US dollar immediately after an ORB poll for the Independent newspaper, showing a sharp swing toward a vote for Britain to exit the EU, was published on Friday (June 10) evening.
Betting odds on Brexit also shortened after the survey, conducted on June 8 and 9, putting the 'Leave' camp 10 points ahead of 'Remain,' the latest in a run of polls to show rising support for a British exit from the EU.
But two surveys published on Saturday (June 11) showed divergent results with one giving a two-point lead to supporters of Britain's EU membership and a second poll showing those in favour of Brexit were one point ahead.
Britons will vote in a June 23 referendum on whether to leave the world's largest free trade area, a decision with far-reaching implications for politics, the economy and trade but contrasting polls have made it difficult to predict the outcome.
An Opinium poll for the Observer newspaper, conducted between June 7 and 10, suggested 44 per cent of Britons back continued membership of the bloc with 42 per cent against and 13 per cent undecided.
Both camps rose 1 per cent compared to last week's poll, which was re-weighted to reduce the impact of a disproportionate number of socially conservative voters.
But a YouGov poll for The Sunday Times showed support for Brexit on 43 per cent with those who wish to remain part of the 28-member trading bloc on 42 per cent, a reversal on the previous survey released on Monday.
Contradictory opinion polls and a failure to predict last year's outright election victory for Prime Minister David Cameron's Conservatives have led financial markets to pay close attention to bookmakers' odds.
On Saturday, bookmaker Betfair cut the odds of a vote to stay, after the ORB poll, giving a probability of 70 per cent, down from 78 per cent earlier this week.
Bookmaker Ladbrokes said the ORB poll had caused it to shorten its odds on Brexit to 9/4 from 11/4 previously, implying a rise in the likelihood of a 'Leave' vote to 30 per cent from 27 per cent.
"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.
However, Peter Kellner, the former president of polling company YouGov, suggested the ORB poll may not be the best indicator of public opinion.
"Tonight's YouGov and Opinium Research polls show little movement. Last night's ORB lurch to 10 per cent Brexit lead looks like an outlier," he wrote on Twitter.
Friday's survey gave the Brexit camp its biggest lead since the poll series started a year ago, the Independent said. But the official Vote Leave campaign reacted cautiously, tweeting:"We don't believe the ORB online poll, our data suggests it's closer to 50-50."
The mixed picture has heightened market jitters about the outcome, with sterling repeatedly reacting to poll results.
Separately on Saturday, Britain's interior and foreign ministers responded to a media report suggesting visa rules for Turkish citizens could be eased by saying there were no plans to change the requirements.
Immigration has been a key driver of support for the 'Leave'campaign and ministers Theresa May and Philip Hammond said in an emailed statement it was "completely untrue" that "the UK is considering granting visa liberalisation to some Turkish citizens."