The EU has strenuously denied that it intends to impose customs checks on Irish exports to the bloc.

After a crunch meeting to resolve ongoing trade tensions in Northern Ireland, the EU’s Brexit commissioner said that Ireland’s place in the single market was “unconditional”.

“We have always shown solidarity with Ireland and we will continue to stand by Ireland, which is the member state most affected by Brexit,” Maros Sefcovic told reporters in London. “This is a matter between the EU and the UK, not between the EU and Ireland.”

Irish sources also denied a report on the Politico news site, which said EU officials and diplomats were discussing an emergency plan to restrict Ireland’s access to the single market.

The idea first surfaced as a possibility in 2019, following the UK parliament’s repeated rejection of the draft Brexit deal and its Northern Ireland protocol.

Under that deal, the EU and UK agreed to carry out checks at Northern Irish ports and airports to avoid any infrastructure along the 500km border with Ireland.

But the EU says the UK has failed to construct proper customs facilities or allow EU officials access to databases on goods moving between Great Britain and Northern Ireland.

Mr Sefcovic said yesterday that “not one” of the things the EU has asked for – including labelling food bound for the Northern Irish market only – has been done.

In March, the UK unilaterally extended grace periods for customs checks on certain foods, parcels and plants sent to Northern Ireland from Britain.

Relations between the two sides have deteriorated significantly since then, with the EU taking legal action against the UK, a case which could end up in the EU courts in early autumn, Mr Sefcovic said.

He added that relations between the two sides are now at a “crossroads” and that the EU could slap tariffs or quotas on UK imports if necessary.

“Our patience really is wearing very, very thin, and therefore we have to assess all options we have at our disposal.

“We are at a crossroads in our relationship with the UK. Trust, which should be at the heart of every partnership, needs to be restored.”

The UK’s Brexit minister, David Frost, said that as a result of the protocol, British businesses are choosing not to sell their goods in Northern Ireland, while medicine manufacturers are threatening to cut vital supplies.

“Further threats of legal action and trade retaliation from the EU won’t make life any easier for the shopper in Strabane who can’t buy their favourite product,” Mr Frost said ahead of yesterday’s meetings. “Nor will it benefit the small business in Ballymena struggling to source produce from their supplier in Birmingham.

“I look to the EU to show flexibility and engage with our proposals so that we can find solutions that enjoy the confidence of all communities.”

One of the most totemic issues is extra checks on chilled meats, including British sausages, which are due to enter into force on July 1, when a second grace period ends.

The UK has not yet confirmed whether it will extend that grace period.

The EU says a temporary veterinary agreement – where the UK would follow EU health and safety regulations – could solve 80pc of the extra checks.

A UK government statement expressed “concern” that there had been no substantive progress on veterinary checks, trusted traders, minced meat, seed potatoes, pet travel and steel quotas.

The UK says it has sent more than 10 papers to the EU containing solutions on these issues, but has received no written response.