The UK's lead minister on the Northern Ireland Protocol has said the Protocol was "not sustainable" if it continued to operate as it currently does.
David Frost also warned that the British government was considering all its options in responding to how the Protocol was implemented.
Speaking after meeting business and community leaders on his first visit to Northern Ireland, Lord Frost said: "Businesses have gone to extraordinary efforts to make the current requirements work, but it is hard to see that the way the Protocol is currently operating can be sustainable for long."
He added: "Solutions must be found rapidly in order to protect the Belfast (Good Friday) Agreement in all its dimensions and to minimise disruption to the everyday lives of people in Northern Ireland - as the Protocol itself requires.
"As the Prime Minister has made clear, we will continue to consider all our options in meeting our overriding responsibility for sustaining the peace and prosperity of everyone in Northern Ireland."
In a statement the UK government said Mr Frost, who was accompanied by the Secretary of State for Northern Ireland Brandon Lewis, had "heard concerns about the level and complexity of paperwork required even on goods remaining in Northern Ireland, notably in the agrifood sector; about disruption to supply chains from Great Britain and consequent diversion of trade; and about the risks associated with the expiry of the grace periods and the introduction of further processes as a result."
Mr Frost urged the EU to take a "risk-based" approach to consignments of food entering Northern Ireland from GB.
UK officials have said this would involve the EU assessing the risk both to the EU’s single market and consumer health when it came to certain categories of food of animal origin entering Northern Ireland from GB.
However, RTÉ reported last Friday that the European Commission had ruled out such an approach.
David Frost urged the EU to "show pragmatism", according to a statement.
The statement said both men spoke to a range of businesses, including those from the aerospace, manufacturing, food and drink, retail, and life sciences sectors.
They also visited Larne Port, where a border control post, or Point of Entry, checks goods moving from Great Britain to Northern Ireland.
Both men were accompanied by Northern Ireland and UK agriculture and veterinary officials, as well as EU staff who are mandated to oversee checks and controls under the Protocol.
The statement said: "Lord Frost and SoSNI also pledged to continue working closely with all sectors of opinion in Northern Ireland, including the NI Executive, as talks with the EU Commission continue.
Brandon Lewis added: "It is vital that the experiences, opportunities and challenges faced by people and Northern Ireland are understood and at the heart of our approach.
"I will continue these constructive and practical discussions in the weeks ahead, supporting Northern Ireland's business needs and minimising the risk of disruptions at a crucial time."
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Earlier, the EU's trade commissioner has said the union is very committed to the successful implementation of the Northern Ireland Protocol and ensuring that there is no hard border on the island of Ireland.
Addressing a virtual event organised by the Institute of International and European Affairs, Valdis Dombrovskis said achieving the smooth functioning of the protocol requires the joint effort of the EU and UK.
The Commission Vice-President said the Brexit trade and cooperation agreement concluded at the end of last year is still in its very early stages and there is a lack of trade data upon which to get a comprehensive picture.
However, he added that some early difficulties have emerged, including those related to the withdrawal of the UK from the single market which is an "unavoidable consequence of the type of Brexit pursued by the UK government", as well as others related to the implementation of the agreement including the Northern Ireland protocol.
"To address these issues the EU plans to be fully solutions-oriented and engage constructively with the UK authorities, keeping a calm but firm approach," Mr Dombrovskis said.
"I would like to reiterate the EU's commitment to making the protocol work and I would add that doing so relies on joint action through the joint bodies and under the withdrawal agreement."
"Ongoing discussions at a technical level will continue in the coming weeks. It is in the strong mutual interest of the EU and the UK to make our trade relationship work."
Mr Dombrovskis also said he noted the concerns of some Irish politicians about the impact of the CETA trade agreement with Canada and the claims that it would enable some corporations to pursue legal actions against states if new legislation impacts their profits.
"Let me be very clear, CETA full protects the right of states and local authorities to regulate and this applies in all fields where public policy objectives are at stake," he told the online audience.
He said the Belgian government had expressed doubts in 2019 and asked the EU Court of Justice to look into the matter.
He added that in its opinion the court confirmed there is no such risk.
"It is important to point this out because the public deserves to have the facts," he claimed.
"There is no hidden agenda in EU trade policy. We simply want it to support our workers and companies, create jobs and work in synergy with our wider objectives."
He also said that the new EU trade strategy aims to be open, sustainable and assertive.
To build on existing trade strengths, Ireland and the EU should continue to make the most of their global trade relationships, he said.
He said the EU-Mercosur agreement would be the largest free trade agreement the EU has ever negotiated and carries a large economic significance, as the union will have first mover advantage.
He also said the EU is in intense discussions with the Biden administration to try to prevent the reimposition of tariffs from 1 June on 232 goods made in Europe, including Irish whiskey, as they enter the US.
Additional reporting Will Goodbody