The euro fell more than 1% against the dollar on Monday and weakened against the yen amid fears that a possible British exit from the European Union could have a negative impact on the eurozone.
Fears over Brexit mounted after London Mayor Boris Johnson said Saturday that he would back the campaign for Britain to leave the EU in a June 23 referendum.
The announcement dealt a blow to U.K. Prime Minister David Cameron’s campaign to remain in a reformed EU after he reached an agreement with the bloc’s leaders late last week.
Earlier Monday a handful of senior Conservative party members said they would also campaign for a British exit and some of the prime minister’s closest business advisers came out against the deal reached with the EU last week.
At least half a dozen of the 20 member Business Advisory Group declined to sign a letter that would argue that the U.K.’s exit from the EU would put the British economy at risk, according to sources cited by Sky News.
Credit rating agency Moody’s Investors Service wrote in a report released on Monday that the outcome of the referendum was “too close to call”.
“In our view, a decision to leave the EU would be credit negative for the UK economy,” Kathrin Muehlbronner, a senior vice president at Moody’s, warned.
Sterling tumbled to six-year lows against the dollar.