The European Union (EU) has admitted the Brexit agreement, allowing trade talks to begin, is not legally binding, describing it as a “gentlemen’s agreement.”

The European Commission said the UK’s representatives had “shaken hands” on the deal, promising pay huge sums and keep the Irish border open, even if it means the whole of the UK stays tied to EU rules and regulations.

On Sunday, on the BBC’s Andrew Marr show, Brexit Secretary David Davis also said the promises made on Northern Ireland were not legally binding unless the UK reached an agreement with the bloc during the second stage of negotiation and a “trade outcome.”

He described it as a “statement of intent” and appeared to suggest the UK could back out of the deal, claiming Philip Hammond, the Chancellor, was wrong when he told MPs last week that the UK should pay a “Brexit bill” even if it did not get a trade deal.

“I’m afraid the chancellor slightly misspoke,” he said. “It says at the beginning of the thing nothing is agreed until everything is agreed. It’s a classical European Union thing.”

However, speaking on LBC radio Monday, he seemed to back away from this position, saying the UK would be “seeking” and open Irish border even if a trade deal did not materialise.

He said: “What I actually said yesterday, in terms, was we want to protect the peace process, we want to protect Ireland from the impact of Brexit for them,” he said.

“And I said this was a statement of intent which was much more than just legally enforceable.

“In other words, of course, it is legally enforceable under the withdrawal agreement. But even if that did not happen for some reason, [if] something went wrong, we would still be seeking to provide a frictionless, invisible border with Ireland.”

Asked about the confusion today, a Commission spokesman said: “Formally speaking the joint report is not legally binding because it is not yet the Article 50 withdrawal agreement.

“But we see the joint report of Michel Barnier and David Davis as a deal between gentlemen and it is the clear understanding that it is fully backed and endorsed by the UK Government.”

He emphasised: “President Juncker had a meeting with Prime Minister May last Friday morning to ascertain that this is the case. They shook hands.

“It’s now for the European Council to decide if sufficient progress has been made to allow the negotiations to proceed to the second phase.”