Britain will be presented with a £50 billion “exit bill” by the European Union as soon as Theresa May triggers Article 50, the chief negotiator for Brussels is warning.

Michel Barnier has told colleagues that the UK must keep paying “tens of billions” annually into the EU budget until 2020.

The bill would include the UK’s share of outstanding pensions liabilities, loan guarantees and spending on UK-based projects.

The demands, which came as the Prime Minister held meetings with other European leaders before being excluded from a dinner at an EU summit, were dismissed by senior Conservatives who refuted the idea of paying such a bill.

Others shrugged off the demands and claimed they were simply the EU’s opening position in an attempted negotiation.