Talks between the EU and UK Brexit negotiators on the Northern Ireland Protocol have ended in Brussels without any apparent breakthrough.
The EU's chief negotiator Maroš Šefcovic called on the UK to "make a clear move towards us" in the area of agrifood checks on goods moving from Britain to Northern Ireland "to reciprocate the big move made by the EU".
He said the EU’s proposals on sanitary and phytosanitary (SPS) controls would lead to "a very significant simplification of certification and a reduction in checks. Identity and physical checks would be reduced by around 80% compared to the checks currently required."
There had been a "useful" discussion at technical level on reducing checks and controls on customs, he said.
In a statement, Mr Šefcovic said there was "genuine urgency" for both sides to agree a package of measures ensuring the licensing of GB medicines, including generic drugs, in Northern Ireland.
"We now need to press on and get this crucial issue across the line. This is a real test of political goodwill.
"The EU, for its part, is confident that our proposed solution, addressing all concerns raised by industry, would bring much needed clarity and foster a positive political momentum," Mr Šefcovic said.
In a statement, Mr Frost said: "We have not yet made substantive progress on the fundamental customs and SPS issues relating to goods moving from Great Britain to Northern Ireland.
"A durable solution here requires goods to be able to move essentially freely into Northern Ireland when both sides agree that they are remaining in Northern Ireland."
He said the UK was seeking a consensual solution that would see "significant" changes to the protocol, and that Article 16 remained on the table.
"If no such solution can be found, we remain prepared to use the safeguard provisions under Article 16, which are a legitimate recourse under the protocol in order for the Government to meet its responsibilities to the people of Northern Ireland," Mr Frost said.
He said there was "potential" to generate some momentum and he welcomed Mr Šefcovic's comments to the DCU Brexit Institute this morning that the protocol had had "unintended consequences" in its application.
Mr Frost said significant gaps remained on "most issues".
On medicines, Mr Frost said there had been progress, but agreement had not been reached.
"Any acceptable solution needs to ensure that medicines are available at the same time and on the same basis across the whole of the UK," he said.
The two men are due to meet again in London next Friday, 26 November.
Article 16 of the protocol allows either side to unilaterally suspend elements of the deal if it creates serious economic, societal or environmental problems.
The arrangement effectively keeps Northern Ireland inside the EU's single market for goods, resulting in some checks for products crossing the Irish Sea from Britain.
Earlier, Mr Šefcovic warned the UK that the current free trade deal was conditional on the Brexit divorce treaty, including the protocol.
Speaking to Dublin City University's Brexit Institute, Mr Šefcovic said the two agreements are "intrinsically linked" and one "cannot exist without the other".
He added: "Settling the divorce has always been, and remains, a precondition for our future relationship.
"It was on this basis that we negotiated, concluded and ratified the Trade and Cooperation Agreement (TCA) on Christmas Eve last year."
There has been speculation that if the UK triggered Article 16 of the protocol, the EU could retaliate by suspending or terminating the TCA.
However, Mr Šefcovic acknowledged that there had been "unintended consequences" from the application of the protocol in Northern Ireland.
He said some of these had been as a result of the kind of Brexit the UK government chose.
In his online address ahead of the meeting, Mr Šefcovic said the EU would not renegotiate the protocol, but would find flexibilities within its legal framework.
He called on the UK to reciprocate what he called the EU's generous offer to reduce checks and controls on goods moving from Great Britain to Northern Ireland.
Mr Šefcovic said the EU was offering a "further facilitation and simplification for east/west trade in the customs field – for example, a 50% permanent reduction in existing paperwork.
"These measures would create a type of 'express lane' which would substantially facilitate trade between all parties. A win-win situation for all.
"It is a unique and completely new model for how goods can be moved from Great Britain to Northern Ireland, one that would strengthen opportunities for people and businesses alike."
The UK has so far cast doubt on the EU's offer to cut agrifood and customs checks.
The European Commission vice president said the EU had listened to businesses and civil society in Northern Ireland and was now proposing an improved exchange of information on how the protocol was being implemented.
This would "make the application of the protocol more transparent, while at the same time respecting the UK's constitutional order.
A website will also be set up to show in a clear and comprehensive way the EU legislation applicable in Northern Ireland.
"We also stand ready to establish dialogue between Northern Ireland stakeholders (authorities, civic society and businesses) and the Commission," Mr Šefcovic said.
"This would involve the creation of structured groups with the participation of experts to discuss relevant EU measures that are important for the implementation of the protocol.
"We are also willing to invite relevant Northern Irish stakeholders to attend some meetings of the Specialised Committees, if this is agreeable to the UK."
British minister confident London could break impasse
Meanwhile, a senior British minister has said he was confident London could break the impasse with the EU over post-Brexit trade arrangements for Northern Ireland without having to trigger emergency measures to safeguard the movement of goods.
"I do believe that there is a constructive approach that has been taken by the (European) Commission," British Minister Michael Gove, who was in charge of implementing Britain's EU divorce deal until earlier this year, told a news conference.
"(Brexit minister) Lord Frost has signalled that, while of course it's always possible that Article 16 may require to be invoked, we're confident we'll be able to make progress without it."
Speaking after meeting Mr Gove at the British-Irish Council, Taoiseach Micheál Martin said he detected a genuine desire from all sides to solve the issues.
Mr Martin said it is time for the UK and EU to "turn the corner" on the damage done to relations following Brexit.
At the BIC news conference in Cardiff, he was asked why UK/EU relations were so poor five years on from Brexit.
Mr Martin said the "underlying reason" was the "historic nature" of Brexit and the length of time the UK had been a member of the EU.
"Inevitably, there will be a long period of adjustment and change," he said.
"There's now a need to turn the corner in the relationship. And by that I mean the macro geopolitical issues are such that we need the European Union and United Kingdom in alignment, working together on the big issues that affect the globe.
"We saw great evidence of that in Cop26 - which I thought was excellently organised and hosted by the British government - and I believe the partnership between the United States, European Union and the UK Government on climate change is the direction of travel.
"That's the spirit that should inform our approach in terms of a sustained constructive relationship between Europe and UK into the future."
Additional reporting Reuters, PA