Boris Johnson warned on Friday night that he was willing to unilaterally breach the Northern Ireland Protocol to keep meat imports flowing ahead of talks with European Union leaders on Saturday.
The Prime Minister’s official spokesman said "all options are on the table" when asked whether he would waive checks on such imports if no agreement is reached by the end of this month.
Doing so would breach the terms of the Northern Ireland Protocol, signed in December, which was designed to avoid checks on the land border between Ireland and Northern Ireland.
Mr Johnson will hold meetings with four European leaders at the G7 summit in Cornwall on Saturday, with tensions over the impact of Brexit on the island of Ireland sure to come up.
He will meet Emmanuel Macron, the French president, at around 8am, followed by Angela Merkel, the German chancellor, and then a joint meeting with Ursula von der Leyen, the European Commission president, and Charles Michel, the European Council president.
Lord Frost, the UK government minister charged with leading on Brexit matters, has travelled to Cornwall and will sit in on the meetings, ready to counter the EU’s arguments. He is expected to tell EU leaders that they are undermining peace in Northern Ireland if they refuse to negotiate a new agreement on how customs checks are being carried out.
A Whitehall source working on post-Brexit policy said: "The Northern Ireland Protocol has to work in a proportionate way which doesn’t disrupt lives in Northern Ireland and undermine the peace process".
Mr Macron, who has been the most vocal of the visiting G7 world leaders over Northern Ireland, appeared to issue veiled warnings as he arrived in Cornwall on Friday.
In one tweet, he posted a photograph of himself with EU leaders in Cornwall, writing: "As always, the same union, the same determination to act, the same enthusiasm! The G7 can begin."
At one point, he was seen deep in conversation with Joe Biden, the US president, who EU leaders hope will intervene on their side to resolve Brexit tensions.
At the heart of the clash is the protocol, which demands custom checks on goods travelling from Britain to Northern Ireland in order to keep the land border on the island of Ireland open.
Britain wants the EU to take a more flexible approach, fearing that the integrity of the UK is undermined by checks. Brussels wants to stick to the original agreement as it negotiates longer-term solutions.
At a press briefing on Friday, Mr Johnson’s official spokesman downplayed the chance of a breakthrough in Saturday’s meetings. A grace period allowing chilled meat – including sausages and mince – to cross the Irish Sea from Great Britain is scheduled to expire at the end of the month
The spokesman said the hope was to find "radical and urgent solutions within the protocol", but added of waiving such checks: "We keep all options on the table".
Meanwhile, Michael Gove, the Cabinet Office minster formally in charge of Brexit issues, said he believed "pragmatic figures" within the EU were willing to work with the Government to resolve difficulties caused by the protocol.
Mr Gove said: "Sometimes when people look at the protocol, they think it is all or nothing at all. We have resolved some of the challenges that have existed but there are other challenges which do need to be tackled effectively.
"I believe there is a willingness within pragmatic figures within the European Union to make sure that we can make these arrangements work so that they do not impact adversely on the lives of people across communities in Northern Ireland."