The ultimate success of British Prime Minister Rishi Sunak's new deal is likely to hinge on whether it convinces the DUP to end a year-long boycott of Northern Ireland's power-sharing government over the original post-Brexit trade rules.

Britain is due to begin clarifying aspects of the reformed trading arrangements for Northern Irish lawmakers this week and the establishment of the consultation group will give the DUP until at least April to make up their minds.

"The group will work independently and will provide me with a report by the end of March," DUP leader Jeffrey Donaldson said in a statement.

"They will want to engage with a broad section of the unionist and loyalist community, the business sector, civic society and others who want to see Northern Ireland prosper within the Union.

The consultation group of party members and "independent thinkers" includes lawmakers from both the regional and British parliaments, former party leaders Peter Robinson and Arlene Foster, businessman Ross Reed and lawyer John McBurney, who also serves on an independent body monitoring paramilitary activity.

Donaldson reiterated that while "significant progress" had been made with the new agreement, key issues of concern remain and that there was "no disguising the fact that in some sectors of our economy EU law remains applicable in Northern Ireland."

He also said that lawmakers were awaiting further legal text to be published to give effect to some of the changes.

While opinion polls have consistently shown a majority of Northern Irish voters - who opposed Brexit - favoured the aim of the original trading arrangements, checks on trade angered many unionists who see it as undermining the union with Britain.

"History teaches us that it is always better to get the right outcome for Northern Ireland rather than a rushed one," Donaldson said.