Boris Johnson has spoken to Joe Biden to congratulate him on his victory over Donald Trump and allay fears Brexit could damage the Northern Ireland peace process, as world leaders lined up to speak to the US president-elect. Johnson was the second world leader to reveal he had spoken to Biden, after the Canadian prime minister, Justin Trudeau, did so on Monday. The German chancellor, Angela Merkel, French president, Emmanuel Macron, and Irish taoiseach, Micheál Martin, said they had also received a call on Tuesday. “I just spoke Joe Biden to congratulate him on his election. I look forward to strengthening the partnership between our countries and to working with him on our shared priorities – from tackling climate change, to promoting democracy and building back better from the pandemic,” Johnson tweeted. Johnson and Biden are understood to have spoken for around 25 minutes from 4pm on Tuesday in a wide-ranging conversation on trade, Nato and democracy. Biden’s transition team said he thanked the prime minister for his congratulations and expressed his desire to “strengthen the special relationship” and “reaffirmed his support for the Good Friday agreement”. Downing Street said Johnson “warmly congratulated” Biden on his victory and “conveyed his congratulations to vice-president-elect Kamala Harris on her historic achievement”, but the official account did not specifically mention Brexit. However, a No 10 source said: “They talked about the importance of implementing Brexit in such a way that upholds the Good Friday agreement, and the PM assured the president-elect that would be the case.” Biden, who has Irish ancestry, has criticised Johnson’s intention to renege on parts of the EU withdrawal agreement in new Brexit legislation, and said that a US-UK trade deal was contingent on upholding the Good Friday agreement. Theresa May was 10th in line when Trump was elected in November 2016, after Ireland, Turkey, India, Japan, Mexico, Egypt, Israel, Australia and South Korea. Trump told May casually that “if you travel to the US you should let me know” – far short of an official invitation. Downing Street said the president-elect had been invited to attend the Cop26 climate crisis summit the UK was hosting in Glasgow next year, and the G7 Summit, also being hosted by the UK next year. Johnson and Biden have never met, although Biden allies have been disparaging about the prime minister. They include a former aide to Barack Obama, who said Democrats had not forgotten about Johnson’s suggestion the “part-Kenyan” former president held an “ancestral dislike of the British empire”. However, Downing Street has emphasised that the two leaders have much in common, in particular a commitment to tackling the climate emergency, which was not shared with the Trump administration. Over the weekend, Johnson said there was “far more that unites the government of this country and government in Washington any time, any stage, than divides us”. He added: “I think now, with president Biden in the White House in Washington, we have the real prospect of American global leadership in tackling climate change. And the UK, as you know, was the first major country to set out that objective of net zero by 2050. “We led the way a few years ago. And we’re really hopeful now that president Biden will follow and will help us to deliver a really good outcome of the Cop26 summit next year in Glasgow.” Senator Chris Coons, a close friend and ally of the president-elect, said he hoped Biden would look beyond the caricature of the UK prime minister. “In my meetings with the prime minister, he’s struck me as someone who is more agile, engaging, educated and forward-looking than perhaps the caricature of him in the American press would have suggested,” he said. “I found an engaging person to meet with and speak to and it’s my hope that president-elect Biden will have a similar experience.” The UK foreign office permanent secretary, Sir Philip Barton, rejected claims that Britain was trying to have it both ways by congratulating Biden but saying that some processes were “still playing out” in the US, a reference to Trump’s refusal to accept the election result. The Labour MP Chris Bryant, a member of the committee, accused Barton of relying on inertia and presiding over a half-hearted and incompetent congratulation. He said he did not see any of the necessary flair coming from the Foreign Office to build the personal relationships on which successful diplomacy rested. PA Media contributed to this report