The European Union will do its utmost to protect Ireland's single market membership, European Commission Vice-President Maros Šefčovič said today.
He also said it is unacceptable that a third country could jeopardise anyone's EU status,
"We will do our utmost to protect the place of Ireland in the single market," he told Euronews.
"It's simply not acceptable that in this case [a] third country would have impact on who are the members of the European Union or what position they have on the single market."
Mr Šefčovič was speaking following a phone call this morning between himself and British foreign secretary Liz Truss on the UK's plans to dismantle the Northern Ireland Protocol.
Ms Truss said the UK would have no choice but to take action on the protocol if the EU did not show what she called the "requisite flexibility".
She said that the situation in Northern Ireland was now a matter of the internal peace and security of the United Kingdom.
In a separate statement, Mr Šefčovič said unilateral action was "simply unacceptable" and that it would undermine Northern Ireland's continued access to the EU's single market.
The Minister for Foreign Affairs, Simon Coveney, said he talked to Maros Šefčovič this evening.
"We are in agreement on UK Government threats of unilateral action and breach of international law.
"The way forward is partnership, dialogue and genuine negotiation, not threats and raising tension. Solutions exist, let's work them out together!"
.@MarosSefcovic: Our objective is to have a stable and positive EU UK relationship based on the international agreements we both agreed, signed, and ratified. Given the current position of the UK government on the protocol, they are not where I would like our relationship to be
— Tony Connelly (@tconnellyRTE) May 12, 2022
Liz Truss earlier said the Northern Ireland Protocol was the biggest obstacle to restoring the power-sharing executive at Stormont.
The UK would have no choice, she said, but to take action.
What that action is was not spelled out, but there has been a crescendo of briefings from London about introducing legislation to disapply parts of the protocol unilaterally.
Mr Šefčovič said such a move would be a matter of serious concern and simply unacceptable.
He reminded his counterpart that with the Russian invasion of Ukraine, upholding the rule of law and abiding by international treaties were a necessity.
One thing they did agree on was that member states are not prepared to give Mr Šefčovič a new mandate in the negotiations.
Ms Truss said this was regrettable, the EU believes this would be caving in to British threats to tear up the protocol altogether.

DUP leader Jeffrey Donaldson said the British government is saying to expect "movement" on the Northern Ireland Protocol "fairly soon".
"I haven't been given clear timelines yet but given the statement that the foreign secretary has made, it is evident that the likelihood of agreement between the UK and the EU in the short term is remote and so I think it is incumbent now upon the government to act and do so quickly," he told media at the Balmoral Show in Co Antrim.
"It's actions I want to see and not just words so we'll be watching and listening very carefully to what the government has to say, but in the end we will judge by what is done as much as what is said," he added.
Earlier, he had repeated his call on the British government to take action.
"The sooner that happens, the better. The protocol is not supported by any unionist MLA elected to the Assembly last week. We can't go on with the situation where there is no consensus at all for this protocol," he told the BBC.
'Goal posts keep on changing' - Taoiseach
The Taoiseach has said that a "unilateral legislative initiative" to circumvent the Northern Ireland Protocol would have a "very destabilising effect on the Good Friday Agreement".
During a meeting of Oireachtas Committee Chairs, Micheál Martin said that such an action would be "very unhelpful" and he has communicated this to British Prime Minister Boris Johnson.
"We had a very frank and honest discussion on Tuesday morning," he said.
Mr Martin said that he believed an intensification and professional engagement between the UK Government and EU, in respect of the operation of the protocol, is attainable.
He said former Brexit negotiator David Frost made an unhelpful intervention when he raised the role of the European Court of Justice the night before the European Commission published proposals on Medicines, SPS and Customs arrangements.
Mr Martin said that "the goal posts keep on changing" and there was a "growing erosion of trust on the EU side". He told the group that there was "lack of clarity as to what the British Government's landing zone is in respect of the protocol issue".
The Taoiseach warned that unilateral action on the protocol would be in breach of an international treaty.
Minister for Foreign Affairs Simon Coveney has branded as "deeply unhelpful" the expressed intention of the British government "to move ahead with domestic legislation" if it does not secure compromises they are demanding regarding the protocol.
He said such unilateral action had "gone down very badly" across the European Union, as well as "ratcheted up tension" in Northern Ireland, which was "completely unnecessary".
'Here we go again'
EU Commissioner Mairead McGuinness has said there is "a sense of here we go again, regrettably" around the unresolved issue of the Protocol.
Speaking on RTÉ's Today with Claire Byrne, Ms McGuinness said there has now been a "ratcheting up of the temperature" from the UK side.
She said Brexit caused the problems that they are now trying to solve in Northern Ireland, and they have negotiated "in good faith" since the referendum and arrived at a conclusion with the agreement of the UK.

"This is about peoples' lives and their livelihoods, it’s about their security of where they are and it’s about opportunity," Ms McGuinness said.
"I do not understand why the British Prime Minister would not want the best for his citizens in Northern Ireland, and the economic opportunities for them are incredibly strong."
Ms McGuinness said there is a capacity to solve these problems if there is an agreement on the UK side to work with what is on the table, and propose more, if that is required, but to do so "with the hand of friendship".
She said if the UK does make a unilateral announcement on the protocol next week, then member states will have to familiarise themselves with the details of this, what it means and what we might have to do as a result.
A border on the island of Ireland "cannot happen and will not happen", she said.
"We cannot allow ourselves as a union of 27 member states that one member, former member state, can dictate how this is resolved by threatening unilateral action."
Additional reporting PA