Cabinet Office minister Michael Gove has joined Boris Johnson in warning that Brussels could break up the UK if MPs do not approve controversial legislation to override parts of the Brexit deal.

Mr Gove echoed the Prime Minister on Saturday in declaring that the EU could put “at threat the integrity” of the Union, and insisted the Government could see off a Tory rebellion.

In incendiary remarks, Mr Johnson said Brussels was threatening to put a “blockade” in the Irish Sea which could “seriously endanger peace and stability” in Northern Ireland.

He was working to quell a plan to amend the legislation from senior Tories who are incensed that it could break international law by overriding the Withdrawal Agreement signed by Mr Johnson in October.

The Prime Minister was joined by Mr Gove in attempts to drum up support for the UK Internal Market Bill ahead of a Commons debate on Monday.

“We’re doing our part – generously – to help protect the EU’s own single market, but we’re clear that what we can’t have even as we’re doing all that is the EU disrupting and putting at threat the integrity of the United Kingdom,” Mr Gove told BBC Breakfast.

“These steps are a safety net, they’re a long-stop in the event, which I don’t believe will come about but we do need to be ready for, that the EU follow through on what some have said they might do which is in effect to separate Northern Ireland from the rest of the United Kingdom.”

Mr Gove conceded that “we are reaching a crunch moment”, but insisted “we have got the support of our own MPs”.

Both Ireland and the EU have warned that Mr Johnson’s plans pose a serious risk to the peace process rather than protecting the Good Friday Agreement.

But he doubled down, and argued it is “crucial for peace and for the Union itself” and said voting the Bill down would reduce the chances of a trade deal with the EU, which is hanging in the balance.

Mr Johnson said the EU would use an “extreme interpretation” of the Northern Ireland Protocol to impose “a full-scale trade border down the Irish Sea” that could stop the transport of food from Britain to Northern Ireland.

“Let’s remove this danger to the very fabric of the United Kingdom. Let’s make the EU take their threats off the table. And let’s get this Bill through, back up our negotiators, and protect our country,” he wrote in the Telegraph.

He also held a conference call with around 250 MPs to try and drum up support for the Bill, and warned them against a return to the “miserable, squabbling days of last autumn”.

But during the call in which there were connection issues and no questions taken by Mr Johnson, further fall-out emerged from the EU.

Leaders in the European Parliament said they would “under no circumstances ratify” any trade deal reached if “UK authorities breach or threaten to breach” the Withdrawal Agreement.

Mr Johnson appeared not to have ended the disquiet within his party during the call, with senior backbencher Sir Bob Neill saying he was not reassured by the speech.

Sir Bob, who chairs the Commons Justice Committee and is tabling an amendment to the Bill which he says would impose a “parliamentary lock” on any changes to the Withdrawal Agreement, said he still contends it contains “objectionable” elements.

“I believe it is potentially a harmful act for this country, it would damage our reputation and I think it will make it harder to strike trade deals going forward,” he told Channel 4 News.

Tobias Ellwood, the Conservative who chairs the Commons defence committee, said on Saturday that “unamended I cannot support this Bill”.

“Already this Bill is damaging brand UK, diminishing our role-model status as defender of global standards. As we go to the wire let’s see more British statecraft-less Nixonian Madman Theory,” he said.

Conservative former leaders Theresa May, Sir John Major and Lord Howard are among the Tories urging Mr Johnson to think again and remove the threat to breach international law.