Boris Johnson must respect the “rule of law” by fully implementing the post-Brexit arrangements for Northern Ireland, EU leaders have said ahead of the G7 summit in Cornwall.

Charles Michel, the president of the European Council, said the behaviour of the prime minister was of increasing concern to EU member states. “It’s paramount to implement what we have decided – this is a question of rule of law,” he said.

The prime minister will hold a trilateral meeting with Michel and the European Commission president, Ursula von der Leyen, in Cornwall.

The framing of the dispute between the UK and the EU as one of respect for the international legal order will chime with the US president, Joe Biden, who arrived in Cornwall on Thursday. Biden is expected to call for both sides to respect the Good Friday agreement.