The pound rose to a six-month high against the dollar early on Thursday after the latest polls supported those in favor of Britain remaining in the European Union, hours before a crucial referendum to decide the country's place in Europe.
Polls by ComRes, conducted for the Daily Mail newspaper and ITV television, and YouGov for The Times newspaper in London showed a last-minute rise in those supporting Britain to remain in the EU.
although several poll results have been too close to call a definitive outcome.
The pound was up 0.6 percent at $1.4802 after touching $1.4847, its highest since the beginning of the year.
A wait-and-see mood was expected to prevail through the rest of the day, dotted by possible bouts of volatility, as the market nervously awaited the British poll results.
The polling will take place between 0600-2100 GMT on Thursday, with the results expected early on Friday.
"It will be hard for the market move until the poll results are released. The pound obviously will take center stage. But other European currencies and particularly dollar/yen also bear watching as the pair will reflect swings in risk sentiment," said Shin Kadota, chief Japan FX strategist at Barclays in Tokyo.
The dollar was up 0.1 percent at 104.595 yen after moving the previous day in a narrow 104.855-104.310 range.
The greenback has sagged against the yen after Tuesday's testimony by Federal Reserve Janet Yellen was seen to have played down the chances of a U.S. interest rate increase in July.
The euro gained 0.2 percent to $1.1324, adding to an overnight gain of 0.5 percent. A slight ebb in prospects of Britain leaving the EU has helped the common currency.
The Australian dollar, seen as a rough proxy of risk sentiment, was up 0.2 percent at $0.7514, not far from a seven-week high of $0.7527 scaled overnight.