The EU’s trade chief said that negotiations on a deal with the UK could not begin until after Brexit.

"There are actually two negotiations. First you exit, and then you negotiate the new relationship, whatever that is," Trade Commissioner Cecilia Malmstrom said.

Between Brexit and the signing of any new trade deal, business between the UK and EU would be conducted under World Trade Organisation rules, she indicated on BBC's Newsnight.

She acknowledged that could damage businesses and economies within the UK and remaining members of the EU: “Yes, but the vote was very clear.”

Earlier this week, she said that she is still aiming to complete negotiations for a sweeping free trade deal with the US this year, despite Britain’s vote last week to leave the 28-nation bloc.

Ms Malmstrom said her team is pressing ahead with talks over the Trans-Atlantic Trade and Investment Partnership and is still negotiating on behalf of Britain as a member state, a condition that will continue for perhaps more than two years as London negotiates an exit.

“We will do whatever we can to make sure that we make as much progress as possible in the coming month, and, if possible, conclude it before the Obama administration leaves office,” Ms Malmstrom said at an Atlantic Council event in Washington.