Leave has the edge in another EU opinion poll.

The online TNS survey found Leave on 43 per cent, Remain on 41 per cent and Undecideds/Would not vote on 16 per cent.

Luke Taylor, head of social and political attitudes at TNS UK said: “With many members of the public still undecided or not planning to vote there is uncertainty around the outcome of the referendum.

“Our latest poll suggests that Leave is in a stronger position than Remain, but it should be noted that in the Scottish Independence Referendum and the 1995 Quebec Independence Referendum there was a late swing to the status quo and it is possible that the same will happen here.”

He added: “Clearly, with a race as close as this, the turnout level among different demographic groups will be critical in determining the result."

TNS asked 2,320 adults in the UK between June 16 and 22.

Another poll conducted by ComRes for The Daily Mail shows Remain with an 8 point lead over Leave.