Britain is currently trying to avoid a trade war with exports of sausages and other chilled meats from Great Britain to Northern Ireland set to be effectively be banned at the end of the month.
With the UK Government insisting it will ignore any ban to prevent further disruption, the European Commission vice-president Maros Sefcovic has warned tariffs could be imposed if that happens.
The Commission vice-president warned that the EU would react “swiftly, firmly and resolutely” to ensure the UK sticks to the Protocol.
Speaking at an EU press conference in London, he said: “Of course, as you would understand, the fact that I mentioned that we are at a crossroads means that our patience really is wearing very, very thin, and therefore we have to assess all options we have at our disposal.
"If the UK were to take further unilateral action in the coming weeks the EU will not be shy in acting swiftly, firmly and resolutely to ensure the UK abides by its international obligations.
“I was talking about the legal action, I was talking about arbitration, and of course I’m talking about the cross-retaliation.
“Unfortunately, there are still numerous and fundamental gaps in the UK implementation of our agreement."
Speaking after his meeting with the UK's Brexit minister Lord Frost Wednesday morning, Mr Sefcovic insisted he was "positive we can find a solution, where there is a will there is a way".
In an interview after the meeting, Lord Frost blamed the EU for a failure to find a solution.
He said: “There weren't any breakthroughs, there weren't any breakdowns either and we are going to carry on talking.
“What the EU is insisting on is we should operate the protocol in an extremely purist way.
“The reality is that it’s a very balanced document that’s designed to support the peace process and deal with the very sensitive politics in Northern Ireland.”
UK sources close to the negotiations added: "Nobody wants to get into a trade war or anything close to it."
“The people in Northern Ireland want solutions not threats".
"But unfortunately we have got used to living in an atmosphere where there are threats."