Britain would be welcomed back into the European Union, but there would be strings attached, the group’s former chief Brexit negotiator Michel Barnier has said.

The former French prime minister, once dubbed the bloc's “Mr Brexit”, pointed out that when the UK left the EU, “they left 600 international agreements.”

Were the UK to rejoin, it would be a case of “welcome back, but there are conditions attached,” he added.

Former French prime minister and ex-Brexit negotiator, Michel Barnier (AFP/Getty)

Andy Burnham recently said it was “possible” Labour’s next election manifesto could include an in-out referendum on EU membership, in his strongest signal yet of his intentions to repair the damage caused by the UK’s departure.

Former Labour leader Neil Kinnock has also said the PM would be the man to lead the UK back into the EU.

Support for rejoining the EU is at its highest level since the Brexit vote, at 61 per cent according to l eading pollster Professor Sir John Curtice says, while Nick Bloom, a…