Ahead of the G7 summit in Biarritz on France’s rugged Atlantic shores, Donald Tusk, president of the European Council of EU leaders, warned that it could be the last chance to heal the battered alliance of powerful “free world” countries.

By the time Emmanuel Macron, the French president, closed the gathering alongside his US counterpart Donald Trump late on Monday, there had been no transformation in the ailing transatlantic relationship — despite several coups de théatre and possibilities for progress engineered by the French leader.

Paris played up the group’s announcement on the potential for talks between Washington and Tehran over the Iranian nuclear programme and $20m to combat Amazon rainforest fires. But longtime G7 observers say a forum intended to tackle the most pressing problems of the global economy and security remains chaotic and sometimes dysfunctional because of tension between the Trump administration and other governments.