Boris Johnson sought to play down any differences with Washington over the way Brexit could affect Northern Ireland after talks with Joe Biden at the G7 summit, as he called the US president “a breath of fresh air”. Speaking to TV reporters after bilateral talks with Biden at the summit venue in Cornwall, where according to Downing Street the pair discussed Covid and the climate emergency, as well as Northern Ireland, Johnson called the discussions “very good”. “There’s no question that under President Biden there is a massive amount that the new US administration wants to do together with the UK, on everything from security working together, protecting our values around the world together, but also on climate change,” the prime minister said. “So it’s a big breath of fresh air. It’s new, it’s interesting, and we’re working very hard together.” The pair also formally agreed a document called the Atlantic Charter, a restatement of common positions in areas including trade, science, human rights and the environment. Before the G7 summit, senior US diplomats in London warned Johnson’s Brexit negotiator Lord Frost that he would inflame tensions in Northern Ireland if he did not compromise with the EU over an impasse about border checks. Johnson expressed confidence that the US and UK could reach agreement on the issue, but gave no details. “One thing we all absolutely want to do … is to uphold the Belfast Good Friday Agreement, and make sure that we keep the balance of the peace process going. That’s absolutely common ground, and I’m absolutely optimistic that we can do that,” he said. Biden was similarly effusive about what he called a “very productive meeting”, referring in his post-talks comments to the “special relationship” between the US and UK, a term of which Johnson is reportedly not a fan. The US president said: “We affirmed the special relationship – that is not said lightly – the special relationship between our people and renewed our commitment to defending the enduring democratic values that both our nations share.” However, Johnson is likely to face considerable pressure from EU leaders at the summit, with the French president, Emmanuel Macron, using a pre-G7 press conference at the Elysée in Paris to describe the UK approach as “not serious”. Asked about British demands for the reopening of negotiations on the Northern Ireland protocol and other tensions between the UK and France, including Channel fishing rights, Macron said it was “not serious to want to have another look at something in July that was finalised in December after years of discussions and work”. Macron, who is also due to hold bilateral talks with Johnson, said: “We have a protocol, an agreement of separation, in the framework of which is Northern Ireland and a trade treaty. It was painstakingly discussed for years and discussed, I remind you, at the initiative of the British who wanted to leave, not the Europeans. “If after six months you say we cannot respect what was negotiated, then that says nothing can be respected. I believe in the weight of a treaty; I believe in taking a serious approach. Nothing is negotiable; everything is applicable.” Earlier, Charles Michel, president of the European Council, said it was “paramount to implement what we have decided” over Northern Ireland. Johnson is to hold a meeting in Cornwall with Michel and the European Commission president, Ursula von der Leyen. Johnson and Biden were all smiles as they greeted each other on camera before their talks, the location of which had to be moved to the conference hotel from St Michael’s Mount, just off the Cornish coast, because of poor weather. When Biden said the pair had both “married above our station”, Johnson replied: “I’m not going to disagree with the president on that or anything else.” He added it was “fantastic” to see Biden. They were meeting before a weekend of talks among the world’s wealthiest countries. Other leaders are due to arrive on Friday. While Brexit does not feature on the formal agenda, Johnson having recently told Atlantic magazine recently: “We’ve sucked that lemon dry,” the US is concerned about Frost’s tactics over the implementation of post-Brexit border checks in Northern Ireland. Frost has made a number of combative interventions in recent days, complaining about the “legal purism” of the EU’s approach to implementing the protocol, which he negotiated, and Johnson signed up to. The government’s former chief law officer, Jonathan Jones, who resigned over Brexit, tweeted: “Is ‘legal purism’ what we now call ‘applying the law’?” Biden’s national security adviser, Jake Sullivan, had hammered home Washington’s message on the way to London on Thursday, telling journalists: “Any steps that imperil or undermine the Good Friday Agreement will not be welcomed by the US.”