Boris Johnson spoke to Irish premier Micheal Martin about the post-Brexit arrangements on Tuesday.
In a Downing Street account of the call, the two leaders agreed on the vital importance of restoring the devolved institutions in Northern Ireland as soon as possible.
The Prime Minister was said to have made clear that the situation in respect of the protocol was now very serious.
The Prime Minister reiterated that the UK Government would take action to protect peace and political stability in Northern Ireland if solutions could not be found
Downing Street spokesman
He also said that the balance of the Belfast (Good Friday) Agreement was being undermined and the recent elections had further demonstrated that the protocol was not sustainable in its current form.
“Despite repeated efforts by the UK Government over many months to fix the protocol, including those sections related to the movement of goods and governance, the European Commission had not taken the steps necessary to help address the economic and political disruption on the ground,” a Downing Street spokesman said.
“The Prime Minister reiterated that the UK Government would take action to protect peace and political stability in Northern Ireland if solutions could not be found.”
However, Tanaiste Leo Varadkar has warned the UK Government against taking unilateral action on the protocol.
Mr Varadkar told RTE: “We can’t have any unilateral action from the UK. This is an international agreement, they have to honour their obligations. I was in the Wirral with Boris Johnson. I know what he agreed to.
“The people of Northern Ireland voted and they did not vote for a majority of MLAs who want the protocol to be scrapped. So the British Government has to have regard to that. This is a democracy and an election just happened.
“The British Prime Minister and the Secretary of State need to be wise to that, if they’re not already.”
An Irish Government spokesman said the Taoiseach had urged Mr Johnson “to engage in intensified EU-UK discussions to address issues relating to the implementation of the protocol”.
The spokesman added: “He set out clearly his serious concerns at any unilateral action at this time, which would be destabilising in Northern Ireland and erode trust.
The Taoiseach stressed to the Prime Minister that the way forward should be through continued engagement with a view to arriving at agreed EU-UK solutions that address the practical issues arising around implementation of the protocol
Irish Government spokesman
“The Taoiseach pointed out that the EU has engaged constructively in the protocol discussions, addressing the issue of medicines, and last October putting forward a substantial package of flexibilities and mitigations, including on customs and SPS arrangements.
“The Taoiseach stressed to the Prime Minister that the way forward should be through continued engagement with a view to arriving at agreed EU-UK solutions that address the practical issues arising around implementation of the protocol.”
In a statement on Tuesday afternoon, European Commission vice president Maros Sefcovic said renegotiation of the protocol was “not an option”, and that unilateral action by the UK would make work on possible solutions “more difficult”.
“The EU has been open to joint work with the UK on implementing the protocol to bring long-term legal certainty and predictability to the people and businesses in Northern Ireland,” he said
“The EU remains open to such discussions. Only joint solutions will work. Unilateral action by the UK would only make our work on possible solutions more difficult.
“The protocol, as a cornerstone of the Withdrawal Agreement, is an international agreement. Its renegotiation is not an option. The European Union is united in this position.”
The Prime Minister and the Taoiseach also discussed the need to restore powersharing in Northern Ireland following the Assembly elections.
The Irish Government spokesman said both leaders agreed on the importance of “having a strong functioning executive in place to deliver for the people of Northern Ireland”.
He added: “The Taoiseach emphasised the importance of the two governments working together in support of the full operation of the institutions of the Good Friday Agreement.”
Mr Johnson also had calls with DUP leader Sir Jeffrey Donaldson who reiterated his position that there must be action on the protocol before his party will enter government.
Speaking after the call, Sir Jeffrey said he was not “setting a time frame” according to which the UK Government must take action on the protocol.
Asked if legislation should be introduced to satisfy bits of the protocol “within weeks”, the DUP leader said: “I’m not setting a time frame for this; what I am making absolutely clear (is) it is decisive action that we need, and we need that to happen quickly.”
On the earliest point at which the DUP could return to powersharing in Northern Ireland, he said: “I’m not measuring this by time frames; I’m measuring it by outcomes.”
He said he had reached out to the EU and was hoping to meet with the EU ambassador to “receive an update from them”.
“In the absence of agreement with the EU, then the UK Government, I think, must act to safeguard the political institutions in Northern Ireland; to safeguard the political process. That has to be the Prime Minister’s priority,” he told reporters.
“To be honest I’ve given the EU months and months and months, we’ve had interminable negotiations, but we haven’t had results, we haven’t had outcomes, we haven’t had decisive action in those negotiations, and that’s what we need.”
Sinn Fein’s Stormont leader Michelle O’Neill has insisted an Executive must be formed now, adding: “The public here can’t be a pawn in the British Government’s game of chicken with the EU.”
Earlier, Foreign Secretary Liz Truss was reportedly set to move to discard large portions of the Northern Ireland Protocol after giving up on Brexit negotiations with the EU.
The Times reported that officials working for Ms Truss have drawn up draft legislation to unilaterally remove the need for checks on all goods being sent from Britain for use in Northern Ireland.
Spoke to Prime Minister @BorisJohnson this morning.
We both agreed on the need to see the NI Executive formed as soon as possible.
On the Protocol, I stressed need to intensify EU and UK discussions, and to avoid any unilateral action.
— Micheál Martin (@MichealMartinTD) May 10, 2022
The law would also ensure businesses in Northern Ireland are able to disregard EU rules and regulations and remove the power of the European Court of Justice to rule on issues relating to the region, the paper said.
Importantly, the Bill would override the protocol agreed by Mr Johnson in 2019 and mean the UK had breached its obligations under the Brexit agreement.
The Times said Ms Truss is understood to have concluded talks with the EU and has been told the proposed Bill could lead to a trade war with the bloc.
It comes after The Sunday Telegraph said Ms Truss faces Cabinet opposition, particularly from Chancellor Rishi Sunak and Communities Secretary Michael Gove, to her plans to rip up the protocol.
The PA news agency was told that Ms Truss is poised to take further action in the coming weeks if negotiations with the EU continue to stall.
But it was argued the protocol will not be completely overridden, with measures instead being considered to ease the issues on the ground in Northern Ireland.
No decisions have been made, it was stressed, but these could include action to address the difference between VAT, rules and courts within the UK on either side of the Irish Sea.