Barack Obama has been warned against intervening in the EU debate by pro-Brexit MPs ahead of his visit to Britain next month.

In an open letter the cross-party group said it would be an "unfortunate milestone" at the end of the US president's time in office should he enter the debate with even a "passive diplomatic recommendation".

Labour backbencher Kate Hoey said the letter aims to caution Mr Obama that "feelings will run high" if he expresses a side in the debate.

"We would certainly never think of visiting the United States and telling the US public how to vote in an election or the amendment of their constitution."