Sterling fell to a one-week low, hurt by month-end selling and polls showing support for those who want Britain to leave the European Union is rising.
A telephone poll conducted by polling firm ICM showed 45% of respondents favoured leaving the EU compared with 42% who said they would vote to stay in the bloc.
A separate weekly online poll by ICM published simultaneously showed voters favoured Britain leaving the EU by 47% to 44%.
Last week's ICM poll put the two camps neck and neck at 45% percent.
"The latest polls have hit sentiment and are driving down sterling," said a spot trader in London.
Both polls came after an ORB poll for the Daily Telegraph showed support for Britain to stay in the EU was at 51%, five points ahead of the leave camp but down from a 13-point lead a week ago.
Sterling fell almost a whole US cent after the polls were released, to $1.4547, from $1.4640 beforehand and down 0.7% on the day.
The euro rose to a one-week high, trading at 76.72 pence, up 0.8% on the day, with volumes picking up after yesterday’s bank holiday in the UK.
The latest polls came after a series of surveys last week showed the "Remain" camp opening up a lead over those favouring Brexit.
The pound climbed to its highest in three-and-a-half months against the euro and a three-week high against the dollar.
"Direction (for the pound) will continue to come from polling data and the dollar over the next 24 hours," said Tobias Davis, head of corporate treasury sales at Western Union.
The dollar was on track for its best monthly performance against a basket of currencies in six months.
It was buoyed by expectations that the Federal Reserve will raise interest rates soon, after Fed Chair Janet Yellen suggested on Friday rates may go up in coming months.
Many doubt the Fed will raise interest rates in June, given the uncertainty from the British referendum. Fed officials have flagged it as a risk factor with a potential exit likely to have an impact on global growth and trade.
Worries about Brexit drove the pound down 11% on a trade-weighted basis between mid-November and early April, when it hit a two-and-a-half year low.
But it has since recovered around half that as investors price out chances of an interest rate cut that some were factoring in if Britain opted to leave.