UK officials have described the latest talks with the EU over the controversial Northern Ireland Protocol as "constructive", as a Brussels delegation prepares to travel to London on Tuesday.
Measures recently proposed by the EU would cut checks on retail agri-food products arriving in Northern Ireland from Great Britain by 80%.
A 50% reduction in customs paperwork is also on the cards.
It is understood, however, that the role of the European Court of Justice (ECJ) in resolving disputes between the UK and the EU remains a key sticking point.
A UK government source said the arrangement "must end", while the European Commission has insisted it will not budge on the issue.
The UK source said: "The talks this week were constructive and we've heard some things from the EU that we can work with - but the reality is that we are still far apart on the big issues, especially governance.
"There's been plenty of speculation about governance this week but our position remains unchanged: the role of the European Court of Justice (ECJ) in resolving disputes between the UK and EU must end."
The source added that "real progress" must happen "soon" to avoid a "process of endless negotiation".
At the end of the week, once several days of negotiations have been completed, Brexit minister Lord Frost and EU Commission vice president Maros Sefcovic are due to meet in Westminster.
The protocol is designed to avoid the introduction of a hard border between Ireland and Northern Ireland, following Brexit.
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