In its world economic outlook, launched today, the IMF, downgraded its forecast for the British economy from its January prediction of 2.2 per cent growth to 1.9 per cent.
“Brexit could do severe regional and global damage by disrupting established trading relationships," the IMF added.
Read more: IMF slashes global growth forecasts
The warning on Brexit was seized upon by George Osborne, chancellor of the exchequer, though there was not a word about the IMF’s comments on austerity in his statement this afternoon:
Today we have a stark warning from the IMF. For the first time they're saying that the threat of Britain leaving EU is having an impact on our economy and they cut our growth forecast as a result.
They say were we actually to leave the EU there would be a short-term impact on stability and a long-term cost to the economy. So this is the clearest independent warning of the taste of things to come if we leave the EU.
I think we're much better off if we stay in the EU; that will make Britain stronger, safer and better off.
The Treasury pointed to the IMF's previous support for Britain's public spending plans, but would not respond to these latest comments.
Brexit campaigners attacked the IMF, and said that the forecasts showed “UK growth to be robust”.
“The IMF has talked down the British economy in the past and now it is doing it again at the request of our own Chancellor. It was wrong then and it is wrong now. The irony is that if we Vote Remain our voice at the IMF will be silenced,” said Matthew Elliott, chief executive at Vote Leave.