In a speech in Brussels on Monday, von der Leyen said any problems in Northern Ireland “result from Brexit,” not from the agreed UK-EU protocol covering trade after Britain’s withdrawal from the European bloc.

“It is disappointing that there was not more recognition from the Commission president of the impact the current operation of the protocol is having in Northern Ireland,” Johnson told reporters on Tuesday.

He added that while the EU “prioritized protection of the single market,” the UK was focusing on “protecting the Belfast Agreement, the Good Friday Agreement, in all its dimensions.”

The Good Friday Agreement – or Belfast Agreement – was struck between the British and Irish governments, and Northern Irish political parties in 1998 to bring about peace in Northern Ireland.

It intended to ease tensions between unionists loyal to Britain and republicans who wanted Northern Ireland to be united with the Republic of Ireland, while also recognising the different groups’ affiliations.

However, unionist critics have said the Northern Ireland Protocol – which effectively puts a trade border in the Irish Sea – threatens to undermine the Good Friday Agreement and cut Northern Ireland off from the rest of the UK.

Earlier this year, some Northern Irish retailers experienced food shortages due to supply issues caused by stringent border checks on fresh imports from the UK that are required under the protocol.

In April of this year, Brexit tensions in Northern Ireland spilled over, and some areas of Belfast descended into rioting.

Last week, David Campbell, the chair of the Loyalist Communities Council, told MPs that the Protocol should be “dismantled” and warned of the “most dangerous situation for many years.”

Von der Leyen has said that there is “no alternative to the full and correct implementation of the protocol” and that it remains the only option to ensure peace in Northern Ireland.

Talks between Brussels and London are ongoing to resolve the issues around the Northern Ireland Protocol.