Barack Obama has been accused of making an "utterly nonsensical" intervention after the outgoing US president urged the UK and EU to hold Brexit negotiations in a "transparent fashion" last night (17 November).
Conservative MEP David Campbell Bannerman told IBTimes UK that it sounded like Obama's "mates in the UK" put him up to the comments.
"When Obama threatened Britain [ahead of the EU referendum] over going to the 'back of the queue' it backfired, and support for Brexit went up not down," he said.
"The idea of demanding global transparency is utterly nonsensical."
The Eurosceptic MEP, who sits on the EU Parliament's international trade committee, said he is "locked in a very hot or very cold room" without pens, paper or a smartphone to see the Transatlantic Trade and Investment Partnership (TTIP) text between the EU and US being negotiated.
"[There is] no transparency whatsoever for TTIP, so why for the UK/EU deal?" he protested.
The Leave.EU group also accused Obama of "parroting" Remain campaign lines, while a spokesman for Ukip told IBTimes UK that the party wishes him well "in his political retirement".
The backlash comes as EU leaders hold a summit with Obama in Berlin, Germany, on Friday. The Democrat is reportedly hoping to assure his European counterparts after Donald Trump secured a shock election victory.
The property tycoon had promised to put the UK at the "front of the queue" for a trade deal with the US, while he gave Theresa May an invitation to meet with him after his inauguration in January 2017.
"If you travel to the US, you should let me know," Trump apparently told the prime minister over the phone on Thursday. The first British politician to meet with Trump after his election was Nigel Farage.
The interim Ukip leader enjoyed an hour-long talk with the fellow right-winger at Trump Tower, New York, on 12 November.
"It was a great honour to spend time with Donald Trump," Farage said. "He was relaxed, and full of good ideas. I'm confident he will be a good president. His support for the US/UK relationship is very strong. This is a man with whom we can do business."
May, meanwhile, has refused to give a "running commentary" on her government's negotiations with the EU.
But the prime minister may be forced to reveal more details about her exit strategy after the High Court ruled that MPs must have a vote on triggering Article 50, the official mechanism to split from the EU.
The government is contesting the decision at the Supreme Court, with a ruling expected in January 2017.