Since the UK left the 27-member trading bloc last year, several issues remain to be resolved between the two sides. One of the biggest sticking points is the part of the Brexit deal covering Northern Ireland. Under the Northern Ireland Protocol, the EU insisted on strict customs controls on certain goods entering the territory from Britain in order to avoid a hard border on the island of Ireland.

However, the invisible trade barrier along the Irish Sea has created chaos for businesses as some products such as chilled meats have been hit with restrictions.

Negotiations over the future of Northern Ireland continued ahead of Christmas, fueling tension between the UK and the EU.

Both sides have recently been tapped for a “full-fledged trade war” by academics Amelia Hadfield and Christian Turner.

The duo analyzed the “Brexit feuds” between London and Brussels since 2017, which they said would likely escalate after a “pre-Christmas standoff”.

Their article, “Brexit Spats with the EU – Britain’s New Christmas Tradition? Was published in the journal Political Insight in November.

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They wrote: “Right now the result is the familiar pre-Christmas dead end.

“The UK continues to view the Protocol as fundamentally unworkable, directly contributing to the growing instability within its own Union.

“Regardless of what was signed, the consequences of its implementation now illustrate for the British side that ‘the initial agreement was politically unacceptable’.

Academics say the two sides have been close to a breakthrough in talks to ease some of the trade concerns over Northern Ireland.

They stressed that carriers and shipping lines want a major reduction in the amount of paperwork, time and costs associated with trade flows between the territory and the rest of the UK.

She will now spearhead talks with the EU following the resignation of chief Brexit negotiator Lord Frost from his post last week.

Just days after receiving her new case, Ms Truss issued a stern warning to the EU about the situation in Northern Ireland.

She reiterated the UK’s threat to unilaterally suspend parts of its deal with the EU after her first appeal with bloc counterpart MaroÅ¡ Å efčovič (pictured) on Tuesday.

She said: “The UK position has not changed.

“We need goods to move freely between Great Britain and Northern Ireland, that we end the role of the ECJ (European Court of Justice) as the final arbiter of disputes between us and that we resolve Other problems.

“We need to step up the pace of talks in the new year. Our preference remains to reach an agreed solution.

“If that does not happen, we stand ready to trigger the Article 16 guarantees to address the very real problems in Northern Ireland and to protect the Belfast (Good Friday) agreement in all its dimensions.”