The safe-haven yen firmed broadly on Monday, hitting a three-year peak against the euro and sterling and a six-week high versus the dollar on concerns Britain could vote to leave the European Union in a referendum two weeks from now.
Uncertainty about the outcome of this week's Federal Open Market Committee policy meeting contributed to the greenback's decline, with the dollar underperforming since the release in early June of a much weaker-than-expected U.S. employment report for May. The jobs data has drastically reduced the chances the Fed will hike rates either in June or July.
Sterling, meanwhile, has been dominated by Brexit concerns since late last year, although other currencies have until now appeared largely protected against worries over Britain's EU future.
With bookmakers and betting exchanges shortening their odds on a vote to leave following a couple of too-close-to-call polls at the weekend, with one putting the "Leave" campaign 10 points ahead, those fears seemed to be spreading on Monday.