David Frost to meet EU Commission vice president to discuss NI Protocol

The minister and the commission vice-president will also “provide a political steer for both teams on outstanding issues”.

Loyalists and unionists are vehemently opposed to the Northern Ireland Protocol, which has created new economic barriers between the region and the rest of the UK.

The arrangements, agreed by the UK and EU as a way to keep the land border on the island of Ireland free-flowing, have been cited as one of the key causal factors behind the violence.

In March, No 10 delayed the implementation of some new sea border processes without EU agreement, prompting the EU to take legal action.

Two weeks ago the UK sent the EU a plan for implementing the protocol.

The BBC understands that the “work plan” document sets out areas where the two sides could work together but does not include dates for when the problematic parts of the protocol – the Northern Ireland part of the Brexit deal – will be in place.

The document has been the basis of technical talks between officials.

No 10 continues to reject the idea of an agreement with the EU on plant and animal health measures (SPS) which would reduce the level of checks on trade between Great Britain and Northern Ireland because it would involve dynamic alignment with European rules in this area.

EU diplomats are now talking about “co-operation” on SPS which sounds less onerous but amounts to much the same thing.

The UK is continuing to suggest an SPS “trusted trader” scheme which would sharply reduce the controls on eligible traders who could show the EU they have secure and auditable supply chains.

The EU rejected this idea at an earlier stage of the Brexit process.

A UK government spokeswoman said: “Technical engagement with the EU in relation to the protocol had continued over recent days and we remain in regular contact at all levels.

“The discussions have been constructive but there are still significant differences that need to be resolved.”