IMF issues stark warning on British exit from EU

Listing the June 23 referendum on membership as one-of-seven downside risks for the world economy, the global financial body said the national vote on whether to stay or go has already created uncertainty for investors.

Negotiations on post-exit arrangements would likely be protracted, resulting in an extended period of heightened uncertainty that could weigh heavily on confidence and investment, all the while increasing financial market volatility.

"If the British economy is hit by the mere risk of leaving the EU, can you imagine the hit to people's income and jobs if we did actually leave?" he said in a statement.

Others, such as David Miliband, a former foreign secretary under Tony Blair who quit front-line politics to head the International Rescue Committee, said the IMF's intervention was right and proper.