The European Union warned “there is no alternative” to the Brexit arrangements put in place for Northern Ireland, as the UK sought an extension to temporary measures allowing sausages to cross the Irish Sea.

Restrictions on shipments of chilled meats are due to come into force when a grace period expires at the end of the month.

The UK has now formally requested an extension, allowing sausages, burgers and mince to continue being sent from Great Britain to Northern Ireland until September 30.

The European Commission said it would “assess” the request, which follows threats from the UK that it could unilaterally extend the deadline if Brussels did not back down.

That could trigger a “sausage war” trade dispute, with the EU warning it would retaliate if the UK acted without agreement.

The looming ban is the result of the Brexit divorce deal signed by Boris Johnson, which effectively keeps Northern Ireland in the EU’s single market in order to avoid a hard border with Ireland.

Under the EU’s rules, shipments of uncooked, chilled meat from a third country – such as the UK since Brexit – are not generally allowed into the single market.

In a statement, the European Commission said it had “already indicated its openness to finding solutions” to the dispute with the UK, as long as they were in line with the Northern Ireland Protocol – the part of the Brexit deal governing the arrangements.

But it warned “for that to happen, the UK must fully implement the Protocol, which is the solution found to protect the Good Friday (Belfast) Agreement, the functioning of the all-island economy, and the integrity of the EU’s Single Market”.

“There is no alternative to the Protocol,” the commission said.

“When looking for solutions, providing stability and predictability for the people of Northern Ireland will be of paramount importance.”

Commission vice-president Maros Sefcovic will seek talks with Brexit minister Lord Frost to discuss the request in detail.

A UK Government spokesman said: “Last month, the Government submitted a written proposal to the EU on extending the chilled meats grace period.

“Today, we have written to the EU to reiterate our request, calling for a temporary extension to 30 September. This would allow movements to continue while we seek to find a longer-term solution with the EU.

“There is no case whatsoever for preventing chilled meats from being sold in Northern Ireland – any ban would be contrary to the aims of the Protocol and the interests of the people of Northern Ireland.”

Without an extension, the ban would come into force during the summer’s loyal order parading season, potentially adding to unionist anger over the Protocol.

On Wednesday, the Prime Minister hit out at the “totally disproportionate” way in which the deal was being implemented and warned the UK would take “the necessary steps” to ensure trade continues freely between Northern Ireland and Great Britain.

Lord Frost  admitted that not much progress was being made towards resolving the row.

“We have asked and suggested to the EU that the right way forward would be to agree to extend the grace period, at least for a bit, to provide a bit of a breathing space for the current discussions to continue and try and find solutions,” he told MPs on Wednesday.

“I still hold out some hope that they might agree to that because it seems a very narrow point to take such a purist view about.”