The British government has said it hopes the EU would not take retaliatory measures if it was forced to unilaterally suspend the special Brexit arrangements for Northern Ireland.
Lord Frost told MPs that in the interests of stability and peace, he hoped that the “EU would not make that more difficult by reacting to it”.
While he said he hoped “that we are not in the situation”, Frost made it clear during an exchange with members of the Commons’ European scrutiny committee that unilateral action was something the UK would consider if it were not able to reach agreement on border checks, mandated in the Brexit withdrawal agreement.
His remarks come as talks between officials in London and Brussels continue, with the UK-proposed checks on food crossing the Irish sea being phased in from the autumn in four stages.
But Frost made clear there was still a gulf in thinking and repeatedly suggested that the EU was undermining the peace process brokered in 1998 by Tony Blair and the then Irish prime minister Bertie Ahern.
“There is a bit of momentum in that discussion [on border checks]. It’s not hugely productive, and we’ll have to see how far we can take it,” he told the committee.
He said a “fundamental problem” was “the way the [Northern Ireland] protocol is undermining the Good Friday agreement rather than supporting it”, echoing the objections of some unionist leaders in Northern Ireland.
He confirmed that the UK was “not keen” on aligning with EU food standards, something former government adviser Shanker Singham has said would lead to 90% of border checks disappearing. That decision was not for “ideological” reasons Frost said, but to enable trade deals with other countries.
He also indicated that there was a dispute over the alternative approach, which was to impose checks on a short list of goods that were “at risk” of going across the border into Ireland and the EU’s single market.
The EU, he said, had to come round to the “heart of the difficulties” and focus on goods that pose a “genuine risk” to the single market and not continue to talk about “superficial realities”.
Frost’s straight-talking style and blunt approach has enraged Dublin and Brussels, who are urging London to take “ownership” of the hard Brexit they pursued.
There was also disbelief that the UK is, as Dublin sees it, stoking “identity politics”, something that was at the heart of the Troubles in Northern Ireland.
Over the weekend Frost urged Brussels to stop “point-scoring” over the Northern Ireland protocol, accusing them of being “purist”. According to internal documents seen by the BBC and the Guardian, the UK wants to phase in border checks on food. Phase 1 from 1 October would involve the introduction of export health certificates for fresh meat. Phase 2, from the end of January, would cover dairy products, garden centre plants, seeds and wine.
Phase 3 would cover fruit and vegetables and pet food, and phase 4 would cover “ambient” foods such as jams, products with a short shelf life and high-risk foods not of animal origin.
The UK says “concrete timelines” would evolve over the coming months, with the timings of phases 3 and 4 determined by the success of the first phases and some technical delivery conditions.
The EU moved to play down tensions, saying it was “making progress” in intensive dialogue with its UK counterparts, adding that the commission’s president, Ursula von der Leyen, was looking for “solutions, not soundbites”.
It said talks with the UK “have been constructive” and “progress” was being made.