The US President Joe Biden ordered the US officials to rebuke the actions of Boris Johnson and the government in the UK for its stance on Northern Ireland and the UK.

America’s charge d’affaires to the UK, Yael Lempert, told Brexit minister Baron David Frost that the UK’s stance on the Northern Ireland Protocol was “inflaming” tensions in Ireland and Europe.

It was a significant diplomatic intervention that threatens to overshadow the G7 summit in Cornwall and Biden's meeting with Johnson on Thursday.

Lempert is said to have issued Lord Frost with a demarche, a formal diplomatic reprimand, at a meeting on June 3 in London.

She relayed to him Biden’s “great concern” over the UK’s approach to the protocol, which was established to prevent a hard Irish border.