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.
Boris Schlossberg, managing director of FX strategy at BK Asset Management in New York, said Brexit has kept the market on edge. He cited the unknown impact on the UK economy, as well as the fact that Britain's exit would "present the first formal challenge to the current global economic order and could spark a much wider and more dangerous fracture of the European Union."
As investors ditched riskier assets, the euro dropped to its lowest against the , 119.01, since February 2013. It was last at 119.92, down 0.3 percent.
Sterling, which was down broadly, also fell to a three-year low of 149.50 yen. The pound last traded down 0.9 percent at 151.09 yen.
The dollar fell against the to a six-week trough of 105.75. By afternoon trade ET, the dollar was down 0.7 percent at 106.22 yen.
Aside from the weak U.S. jobs data for May, Brexit uncertainty is also seen as "giving the Fed more cover to maintain low rates for longer," said Joe Manimbo, senior market analyst at Western Union Business Solutions in Washington.
A shortage of dollars and safe-haven demand for the yen globally are stretching certain dollar-based rates to levels more associated with periods of extreme market stress, raising a red flag for the wider financial system. The benchmark 3-month dollar/yen FX basis-swap was last trading at -102.25, the lowest in at least seven years.