No-deal Brexit back on table if UK triggers Article 16, Liz Truss warned

Brussels has threatened to collapse the post-Brexit trade deal if Liz Truss triggers Article 16 of the Northern Ireland Protocol when negotiations resume.

Maros Sefcovic, a European Commission vice-president, said the EU would seek to scrap the post-Brexit trade deal if the Foreign Secretary unilaterally overrides the measures designed to prevent a hard border.

Ms Truss has already told her EU counterpart she will not drop Lord Frost's threat to trigger Article 16 and "remained prepared" to suspend areas of the Brexit deal relating to the province if the bloc failed to compromise.

The UK's repeated threats to trigger Article 16 are "an enormously disruptive element in the negotiations", Mr Sefcovic told German newspaper Der Spiegel in a warning shot to Ms Truss.

"You try to achieve something together, and – boom – there's the threat of Article 16 again," he said. "That goes to the heart of our relationship. This would initially have serious consequences for Northern Ireland. In no region of Great Britain is the economy currently developing as well as there.

"All this would be jeopardised if Northern Ireland lost access to the EU's internal market, and I don't want to imagine the consequences for the fragile peace on the island of Ireland. All this would have serious consequences for EU-London relations."

The Government and the EU have been at a months-long standstill in attempts to renegotiate the protocol, which Downing Street believes has had a chilling effect on trade in the region. To keep the Irish land border open, Northern Ireland follows around 300 EU Single Market rules, creating trade friction in the Irish Sea.

In the interview, Mr Sefcovic raised the prospect of the EU ripping up the post-Brexit trade deal, agreed on Christmas Eve last year, if Britain moved to override customs controls on products shipped from the rest of the UK.

He argued that the protocol was "the most complicated part of the Brexit negotiations and is the foundation of the whole deal", adding: "Without the protocol, the system collapses. We must prevent that at all costs."

Ms Truss and Mr Sefcovic are expected to reopen talks in the first half of next month, with the Foreign Secretary having told colleagues she is keen to get off to a quick start in her efforts to renegotiate the protocol. She was appointed lead negotiator when Lord Frost resigned as Brexit minister because of concerns over Number 10's "direction of travel".

Mr Sefcovic, who had an often tense relationship with Lord Frost, said he would approach the talks with pragmatism.

He blamed the trade barriers between Northern Ireland and Great Britain on the hard Brexit pursued by Boris Johnson, saying: "After all, it was the British Government that wanted to leave the EU internal market and enact its own rules again.

"The simple truth is that the further our rules move away from each other, the more complicated trading becomes. And if such a large economy as the British wants free access to our internal market, we must ensure that our standards – such as environmental or consumer protection – are adhered to and that competition between British and EU companies remains fair."

Brussels has presented a package of measures, which it believes will cut customs red tape by up to 80 per cent on some goods, to ease the burden of controls on the unionist communities in Northern Ireland.

But Number 10 wants to go further by diminishing the role for the European Court of Justice in a new-look protocol – a proposal the EU has rejected.