The UK Government is “keeping all options on the table” to resolve issues with the Northern Ireland Protocol, including triggering a clause which would allow the unilateral overruling of the agreement.

Brexit minister Lord Frost told Parliament’s European Scrutiny Committee on Monday that the agreement, which was negotiated to avoid a hard border with Ireland by effectively keeping Northern Ireland in the EU’s single market for goods, “isn’t sustainable in the way it’s working at the moment”.

And he said the only way to make it work was to “hugely reduce or eliminate the barriers between Great Britain and Northern Ireland, goods moving in that direction”.

It comes after a grace period to allow chilled meats to continue to be moved to Northern Ireland was extended until September 30, however there is still no agreement between the UK and EU on how to resolve disputes around the agreement in the long term.

Leader of the DUP Sir Jeffrey Donaldson took part in a virtual meeting with European Commission vice president Maros Sefcovic on Monday morning.

He described his message to Mr Sefcovic as “simple – the protocol has not worked” and insisted that the UK Government and European Union must renegotiate.

But European Commission president Ursula von der Leyen has said the protocol is not the problem behind a series of issues the region has faced in recent months.

Lord Frost told the European Scrutiny Committee: “All options are on the table, we’ve always said that and keep saying it, and we don’t rule anything out.

“At the same time, what we haven’t yet tested is whether a fundamental rebalancing of the way the protocol works is possible. At the moment we’ve been talking about, with the EU, essentially, the problems that the current application has thrown up.”

But he said: “What we haven’t yet talked about is are the arrangements that produce those problems also reasonable or not, and I think that’s the kind of discussion we’ve got to try and get on to.”

I think what I can say at the moment is that it must work in a different way if we’re to find the stable route going forward

He said “the core of the problem” remains that “the boundary between Great Britain and Northern Ireland is too dissuasive, too complicated, too chilling of identity in various ways, and that’s what’s got to be solved, I think, in terms of direction of travel.”

Lord Frost said he was unable to reveal whether the Government would be looking to change the text of the protocol, or changes to EU legislation, ahead of an expected announcement on Wednesday.

He said: “I think what I can say at the moment is that it must work in a different way if we’re to find the stable route going forward.”

And asked directly whether this meant the UK could trigger Article 16, which allows parts of the deal to be unilaterally overridden, he said “all options remain on the table now and in the future”.

The barriers and distortion to trade within the UK internal market brought about by it must be swept away and not replaced

He told the committee: “If the workings of the protocol are undermining the Belfast Good Friday Agreement, then the protocol isn’t doing its job.

“And one of the core elements of the Belfast agreement was that all the different strands, the three strands, had equal status, and at the moment, it feels as if the east-west elements of the protocol are not working as well as north-south, and clearly that imbalance is not what the Good Friday Agreement intended, so that’s the core of the problem.”

Unionists strongly oppose the additional checks on goods arriving into Northern Ireland from the rest of the UK as undermining the union.

And leading supermarkets at the weekend hit out over fears of the impact on supply lines into the region once various grace periods on checks end.

Sir Jeffrey said: “The barriers and distortion to trade within the UK internal market brought about by it must be swept away and not replaced.

“We have pressed the UK Government to that end. Both the Government and the EU must now renegotiate.”

Sir Jeffrey said if the EU is “unwilling to recognise the harm caused by the protocol” then the UK Government “must take appropriate unilateral action using Article 16”.

Last week the DUP set out seven tests on the protocol.

They include a promise of no checks on any sort of goods being sent to Northern Ireland from Great Britain and compatibility with the Act of Union which says all parts of the UK should be on equal footing when it comes to trade.

However Sinn Fein president Mary-Lou McDonald said any thought of changing the protocol is “fanciful”, adding it is “here to stay”.

She described the protocol as “the answer, not the problem”.

“The protocol isn’t going anywhere, it has been negotiated, it has also been signed off not just by the European side but also by the British Government, so I think, with respect, any assertions that the protocol can be abolished are fanciful, that’s not going to happen,” she told reporters in Belfast.