Boris Johnson has said it would be “preposterous” for Brussels to launch a trade war over “trivial” planned changes to the Northern Ireland Protocol – as senior EU figures warned of the damage they could cause.

The government is preparing to table legislation to override parts of the deal, which governs Northern Ireland’s post-Brexit trading arrangements despite claims that the move will breach international law – threatening a major row with Europe.

Ireland’s foreign minister Simon Coveney and European Commission vice president Maros Sefcovic both reiterated their opposition to the deal after speaking to Foreign Secretary Liz Truss.

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A spokesman for Mr Coveney said it “marks a particular low point in the UK’s approach to Brexit”.

But in an interview with LBC, Mr Johnson said: “It’s a bureaucratic change that needs to be made. Frankly it’s a relatively trivial set of adjustments.”

The PM said it would be a “gross, gross overreaction” and “preposterous” for the European Union to respond by imposing trade restrictions.

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Earlier, Environment Secretary George Eustice rejected criticism from those who say the changes are not needed as the protocol as it stands is working.

The protocol was agreed by the UK and EU to avoid a hard border between Northern Ireland and the Republic after Brexit.

Northern Ireland remains under some EU rules and there are checks on goods coming from Great Britain, effectively creating a border in the Irish Sea.

Hardline Brexiteers have said this undermines Northern Ireland’s place in the UK and Democratic Unionists have refused to enter power-sharing until the issue is addressed.

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0:30

Brandon Lewis: We want to fix problems of Protocol

Ms Truss said on Monday after her discussions with Mr Sefcovic to discuss the legislation that the UK still wanted to see a negotiated solution but that “the EU must be willing to change the protocol itself”.

Mr Eustice rejected the claims of those who say that the protocol is working, suggesting that was only because the deal had still not been implemented in full.

“There are some standstill provisions that we have which means that we’re not actually doing any checks at the moment when it comes to products going from GB to Northern Ireland,” he said.

“There are many other grace periods that are only temporary.

“What we need is some longer term permanent solution and that’s what this bill will set out.”

Asked about the CBI’s concerns, he said: “I work very closely with lots of different businesses.

“The truth is that most of the major retailers – like Marks & Spencer and Tesco and others, who are sending quite complex, composite loads to Northern Ireland – they know that the protocol if implemented in its full way wouldn’t allow their business models to really continue.

“So businesses generally do want us to sort this problem out.

“Obviously the CBI’s a lobby group – it can set out its position – but we’ve obviously got access to the right legal advice as to what we’re doing and we obviously have much more knowledge.

“We draw comment from a much wider pool of businesses than the CBI represents.”

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3:35

What is the Northern Ireland Protocol?

Ms Truss last month laid out the plan for legislation to override parts of the protocol, citing the need to respond to the “very grave and serious situation”.

She said the bill would preserve elements that were working, while fixing those that were not – the movement of goods, goods regulation, VAT, subsidy control and governance.

It could allow ministers to remove customs processes for goods moving within the United Kingdom and enable the frictionless movement of agri-food goods staying within the UK.

It could also see businesses in Northern Ireland given the ability to choose whether to follow UK or EU regulations, depending on who they are trading with.

But Britain has been warned that unilaterally pulling out of the protocol could put the wider Brexit deal at risk, provoking a trade war with Europe, while also breaching international law.

‘Lawful’ and ‘correct’

Northern Ireland Secretary Brandon Lewis insisted that the new bill is “lawful” and “correct” but there is likely to be some opposition from within Tory ranks.

According to the Financial Times, a note has been passed among those against the bill, saying: “Breaking international law to rip up the prime minister’s own treaty is damaging to everything the UK and Conservatives stand for.”

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Mr Lewis told Sky News’ Sophy Ridge on Sunday: “What we’re going to do is lawful and it is correct.

“We will be setting out our legal position on this. People will see that what we’re proposing resolves the key issues within the protocol that don’t work.”

But shadow chancellor Rachel Reeves said: “This government seems to be developing a record for law-breaking and it is not one that the Labour Party can support.”

Downing Street has said it will share only “a summary” of the legal advice it received with the public.