Boris Johnson and Joe Biden on Thursday attempted to smooth over their differences on Northern Ireland in their first face-to-face meeting at the G7 summit of western leaders in Cornwall.

The US president’s “deep” concerns were conveyed directly to London earlier this month by America’s most senior diplomat in Britain, who warned the UK to stop inflaming tensions in Northern Ireland over new Brexit trading rules.

But both leaders spoke warmly of their first meeting, with Johnson hailing the talks with Biden as “very good” and describing the US administration as “a big breath of fresh air”. The prime minister added there was “absolutely common ground” on protecting peace in Northern Ireland.

Biden described the 20-minute meeting as “very productive” and said “we affirmed the special relationship between our people and renewed our commitment”, which he added was “not said lightly”.

Downing Street said “the leaders agreed that both the EU and the UK had a responsibility to work together and to find pragmatic solutions to allow unencumbered trade between Northern Ireland, Great Britain and the Republic of Ireland”.

The EU is threatening trade sanctions if Johnson unilaterally breaks promises he made relating to Northern Ireland, and the G7 summit host will face awkward encounters in the coming days with the leaders of France, Germany, Italy and the EU itself.

Yael Lempert, the US chargé d’affaires in London, is reported to have urged Britain to make “unpopular compromises” if necessary to ease tensions over the so-called Northern Ireland protocol, part of the 2019 Brexit treaty which seeks to avoid a hard border on the island of Ireland.

According to a UK government note seen by the Times, Lempert told Lord David Frost, Brexit minister, on June 3 that the UK was “inflaming” tensions in Ireland and Europe with its rhetoric over certain checks at ports in Northern Ireland.

The memo said the US “strongly urged” Britain to come to a “negotiated settlement”, even if that meant “unpopular compromises”. The UK note of the meeting said Lempert urged Britain to keep things “cool”, suggesting Britain had been “inflaming the rhetoric”.

It added: “Lempert said the US was increasingly concerned about the stalemate on implementing the protocol. This was undermining the trust of our two main allies.”

The revelation of the meeting confirmed the anxiety felt by Biden over the UK-EU stalemate over the border issue in Northern Ireland. Jake Sullivan, national security adviser, said the president had “deep” concerns over the future of the peace process in the region.

A senior administration official told the Financial Times the US had raised its concerns over Northern Ireland with the UK in a private message ahead of their summit. But the official said the discussion was not directed by the president and “was not heightened”.

The official added: “As with any ally we have diplomatic conversations about areas where we have concern at many levels.”

French President Emmanuel Macron lambasted the UK for seeking to renegotiate the Northern Ireland protocol only months after agreeing it. 

“You can’t just decide to review in June what was finalised in December after months of work and negotiations,” Macron said at a news conference ahead of the G7 summit in Cornwall and a planned meeting with Johnson. “This was painfully discussed for years.”

He said: “I believe in treaties. I believe in being serious. Nothing is renegotiable, everything should be applied.” 

Johnson claims that the EU’s demands for checks on goods moving between Great Britain and Northern Ireland are too onerous and are disrupting trade while inflaming tensions in the pro-UK unionist community.

Earlier on Thursday, Ursula von der Leyen, the European Commission president, told a press conference in Brussels that she and European Council president Charles Michel would be holding a meeting with Johnson in Cornwall to discuss the situation. She insisted the EU had “bent over backwards for years” to find a solution that works for everyone in Northern Ireland. 

The issue is a major distraction for Johnson ahead of the start of the summit and overshadowed the announcement of a new US-UK “Atlantic Charter”, an attempt to evoke US-UK wartime co-operation and the 1941 charter signed by Churchill and Roosevelt that mapped out a new world order.

Johnson and Biden met each other for the first time on a deck overlooking St Ives Bay. The US president told the prime minister he was “thrilled” to meet his new wife, Carrie Johnson. “I told the prime minister we have something in common: we both married above our station,” he said.

The prime minister responded “I’m not going to disagree with the president on that or anything else.”

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