The European Commission warned Britain that any further unilateral action over the Northern Ireland Protocol was unacceptable at a meeting last night.
Maros Sefcovic, the commission vice-president, told David Frost that “solutions can only be found through joint actions and through joint bodies”.
Rather than the unilateral extension of grace periods on some customs checks in the Protocol, which Brussels says is a violation of international law, “mutually agreed paths towards compliance are key”, the commission said.
The Protocol prevents a hard border on the island of Ireland after Brexit by introducing a customs border in the Irish Sea. It means that Northern Ireland must continue following some EU rules in order to prevent extra checks.
“The Vice-President stated clearly that the implementation of the Protocol is a joint endeavour, which leaves no space for unilateral action,” a commission statement said.
“Only joint solutions, agreed in the joint bodies established by the Withdrawal Agreement, can provide the stability and predictability that is needed in Northern Ireland,” the commission said.
Mr Sefcovic said that EU legal action against the UK for breaching the Protocol would continue but Brussels has granted a British request for an extension on a deadline to respond to a letter triggering the lawsuit.
Last night’s meeting between Mr Sefcovic and Lord Frost came after a couple of weeks of technical work between officials on the implementation of the new customs arrangements for Northern Ireland.
Good progress was made in that technical work, according to the commission, but both sides have stressed that significant differences remain and that any breakthrough is some way off.
“The meeting took place in a constructive, solution-driven atmosphere.
[...] both teams were given a political steer for the technical-level discussions that should further intensify over the coming weeks."
Lord Frost was served asparagus soup with scallops, followed by grilled sea bass and mascarpone and vanilla ice cream, after arriving at the Berlaymont building at 7.30pm local time.
The meeting lasted two and a half hours and Lord Frost flew back to the UK last night.
A UK statement said that “some positive momentum had been established but a number of difficult issues remained.”
Britain insists that its unilateral actions in extending the grace periods on food products and parcels is lawful and made in good faith. The UK argues that preventing some GB trade to NI would disrupt everyday life in Northern Ireland.
“Lord Frost repeated the UK’s commitment to working through the joint bodies provided for by the Withdrawal Agreement. He underlined that any solutions had to be consistent with the overriding commitment to respecting the Belfast (Good Friday) Agreement in all its dimensions and to ensuring minimum disruption of everyday lives in Northern Ireland,” the statement said.
The EU and Britain have identified 27 different issues in relation to Northern Ireland's contested post-Brexit trade arrangements, some of which are more difficult than others and require political solutions, Ireland's foreign minister Simon Coveney said on a visit to London on Thursday.
Mr Sefcovic has suggested that aligning EU and UK animal health rules could remove the need for many border checks but Britain has rejected that.
It wants its rules to be deemed equivalent, of a similar standard, to Brussels' rather than exactly the same and changing to match them over time.