Reuters reported that four-fifths of Britain's major companies have taken steps to hedge against the risk that a vote to leave the European Union will knock more than 10 percent off the value of sterling, a poll of almost 800 of Britain's top 1,000 companies showed on Wednesday.

The poll by banking researchers East&Partners, seen by Reuters before its release later on Wednesday, by contrast suggested 83 percent of small and medium-sized firms think sterling will be unharmed by a vote for Brexit.

Only 22 percent said they were hedged against such a risk.