The UK’s three-month truce with the EU is a “sticking plaster” that addresses just a “tiny part of the problem” with the Northern Ireland Protocol, Lord Frost has suggested, as he warns that mainstream unionist support for the agreement has “collapsed”.

In an interview with The Telegraph, the minister responsible for Brexit said the agreement was failing to “reflect the balance that was in the Good Friday Agreement” and therefore “is not working”.

The Government’s “worry”, he said, was that the UK and EU “just lurch from date to date, and crisis to crisis, and find sticking plaster fixes, but never deal with the underlying problem”.

He claims that some EU leaders are more focused on “process” than on addressing the problems that have arisen, such as the recent “sausage wars” row, and warns that potential disorder in Northern Ireland must be “factored in” to their consideration of the issue.

Lord Frost’s remarks will provoke a fresh row with Brussels, which has insisted on “full implementation” of the protocol, the part of the Brexit deal which covers the goods trade on the island of Ireland.

Last week, the EU agreed to a temporary extension of the grace period in which shipments of chilled meat, such as sausages, can enter Northern Ireland from Great Britain.

Brexit sausage war explained

But the bloc warned it would not provide a “blank cheque” for the suspension of post-Brexit Irish Sea checks, with João Vale de Almeida, the EU’s ambassador to the UK, stating: “We remain firm on the full implementation of the protocol.”

Mr Vale de Almeida also insisted the EU would “continue to seek creative solutions” to the problems identified by the Government.

Lord Frost is concerned the protocol is having a “chilling effect” on firms, with some drug companies preparing to stop supplying some medicines to Northern Ireland, and “some companies in Great Britain … simply giving up and saying it’s too much trouble to engage with all the paperwork and bureaucracy”.

He added: “We have seen disorder, albeit fairly low level, at Easter, and we’ve seen quite a lot of protest across Northern Ireland, in various ways, amongst unionism. That just has to be factored in.

“Nobody wants to see that situation get any worse and it’s absolutely not our wish that it should. The best situation is one of calm and we have to show that what we can do together as the UK and EU is capable of responding to those political demands.”

Lord Frost’s remarks came in an interview conducted on Friday as he prepared to join Boris Johnson at Chequers for talks with Angela Merkel, the outgoing German chancellor.

Downing Street said the Prime Minister “reiterated the need for a permanent arrangement on the Northern Ireland Protocol that protects the Belfast (Good Friday) Agreement and safeguards Northern Ireland’s place in the United Kingdom.”

Lord Frost said of last week’s temporary truce: “The problem is, although it was good to have reached that agreement to avoid the cliff edge on June 30, it is only a tiny part of the overall problem. There is a long list of issues thrown up by the way that the protocol has been implemented. This is just one, it was the most immediate, we’ve resolved it for now. But there’s still lots to do.”

Protocol ‘doesn’t relect the balance in the Good Friday Agreement’

He said the need to address the problems with the protocol was “quite urgent”, adding: “Support for the protocol has collapsed in unionism. The latest polling shows that there’s a 50/50 division in Northern Ireland. That’s just not a stable basis to proceed on. That is the problem.”

He continued: “It just doesn’t seem unreasonable to us to say, these arrangements aren’t working out quite as we both thought, look at the effects and the way it’s playing out, we really should take another look at how it’s happening.”

Lord Frost said that the protocol “as it’s being operated at the moment doesn’t reflect the balance that was in the Good Friday Agreement and it was intended to. If it isn’t supporting the Belfast Good Friday Agreement and helping that work, then the protocol itself isn’t working.”.

He added: “Obviously not every EU leader is an expert in Northern Ireland and we wouldn’t expect that. I think there are varying degrees of understanding of the issue and the status of Northern Ireland. Obviously Ireland itself has a very direct interest in this and has been encouraging of the sense that there’s an issue here and we take it seriously.

“I think others are perhaps a bit more focused on the process thing, that we should just implement the protocol and everything will be fine.

“We don’t think that quite deals with the situation as we now have it.”

In a joint article in Saturday’s Irish Times, Lord Frost and Brandon Lewis, the Northern Ireland Secretary, warned that the current implementation of the protocol risked “damage” to the Good Friday Agreement.