The International Monetary Fund chief has said a vote by the UK to leave the European Union would have "pretty bad, to very, very bad" consequences, BBC News reports.
Christine Lagarde said she had "not seen anything that's positive" about Brexit and warned that it could "lead to a technical recession".
She echoed similar comments made on Thursday, May 12 by Bank of England governor Mark Carney.
Vote Leave said the IMF had been wrong in the past and were "wrong now".
The IMF said in a report on the UK economy that a leave vote could have a "negative and substantial effect". It has previously said that such an outcome could lead to "severe regional and global damage".
Lagarde said the Fund had a duty to assess the risks of Brexit. It has a mandate to oversee the international monetary and financial system.
Brexit was not just a domestic issue but an international one as well, she told a briefing at the Treasury attended by the Chancellor, George Osborne.
"I don't think that in the last six months I have visited a country anywhere in the world where I have not been asked 'what will be the economic consequences of Brexit?" she said.
