EU institution leaders will tell British Prime Minister Boris Johnson at the G7 summit that Britain and the EU had both agreed the protocol governing Northern Ireland trade arrangements and that Britain must apply it and not make unilateral changes.
European Commission president Ursula von der Leyen said on Thursday that the protocol was the "one and only solution" to avoid a hard border on the island of Ireland and that she still saw "fundamental gaps" in Britain's implementation of it.
"We will discuss that in a trilateral meeting in Cornwall together. We are determined to do everything to keep peace and stability on the island of Ireland. It is important that there is deep respect for the protocol," she told a news conference.
She said both sides had also signed up to a dispute settlement mechanism, with potential for remedial measures that can be taken, but did not specify what action the EU would take if Britain failed to respect the protocol.