Michel Barnier has insisted he is not conducting parallel Brexit negotiations with Jeremy Corbyn as the Labour leader faced pressure to give his party membership a say on his plan for the UK’s divorce from Brussels.
Mr Corbyn met with Mr Barnier in London on Monday and he allegedly told the European Union’s chief Brexit negotiator that he was open to keeping Britain in the customs union after withdrawal.
The meeting prompted concerns that Labour was seeking to undermine Theresa May, the Prime Minister, as she seeks to negotiate the UK’s exit from the bloc.
But Mr Barnier yesterday moved to downplay the significance of his audience with the Labour leader as he said: “I am not negotiating with Jeremy Corbyn.”
Mr Barnier’s remarks came amid growing calls for Mr Corbyn to consult the Labour Party membership on what the UK’s post-Brexit relationship with the EU should be.
A survey of the nation’s party members, released at the start of the year, revealed almost nine in 10 want a soft Brexit with continued membership of the single market and the customs union.
The survey results place the party membership at odds with Labour’s existing Brexit policy which is for the UK to retain the benefits of the single market and form a customs union with the EU.
A group of 30 pro-European Labour MPs and campaigners have reportedly written to the party’s ruling National Executive Committee (NEC) asking for the membership to be consulted on the issue.
Remain-backing MPs hope that such an exercise could force Labour to water down its existing policy and back a softer Brexit plan to keep the UK in the single market and customs union.
Labour’s Brexit plan has come under increasing scrutiny after the emergence of a memo circulated to European nations which suggested Mr Corbyn had told Mr Barnier he was open to continued membership of the customs union.
Mr Corbyn apparently promised Mr Barnier that he would run the Brexit talks "very differently" if he came to power.
Labour has denied the contents of the memo but the row has sparked concerns about how much influence Mr Corbyn has over the negotiations.
Mr Barnier addressed the issue at a press conference in Brussels on Friday and said: "Mr Corbyn is an important figure in British political debate. He asked to meet me and I have no reason not to meet him.
"I can tell him where we stand but I am not negotiating with Jeremy Corbyn.”
In response to suggestions the meeting on Monday was an attempt to undermine Mrs May, Mr Barnier said his "door is open to everybody" but negotiations would only take place with the UK Government.
Labour has faced accusations of adopting a deliberately ambiguous Brexit policy to avoid alienating its largely Remain-backing membership.
Mr Corbyn could be forced to change tack if the NEC acts on the letter sent to it by pro-European MPs demanding that members are consulted on Brexit.
Heidi Alexander, a Labour MP who chairs the Labour Campaign for the Single Market and one of the signatories to the letter, told The Guardian: “No matter what your views on Brexit – whether you think we should stop it altogether or find a way to stay as close as possible - it is quite astonishing to think that in the 12 months leading up to the country’s scheduled departure from the EU, the Labour Party doesn’t have a dedicated policy group to consider the issue.”
The party has reportedly set up groups to allow the membership to have a say on a variety of policy areas but Ms Alexander said Brexit was the “elephant in the room”.