Northern Ireland's former first minister and ex-DUP leader Peter Robinson has said unionists cannot oppose the Northern Ireland Protocol at the same time as being part of an administration that implements it.
In an article in the Belfast News Letter, Mr Robinson said unionists have to decide whether scrapping the protocol is more important than the continued operation of the Stormont Assembly.
"If there is the stomach for defiance then, in truth, you cannot try to ditch the protocol and administer it at the same time," he said.
"How comfortable are unionists with that and the consequences that may flow from it?
"Is the scrapping of the protocol more important than the continued operation of the Assembly? A choice may have to be made."
The former DUP leader warned of the potential for violence from those opposed to the protocol "lurking in the background".
"At present only the pandemic is suppressing the outpouring of frustration and the protests that accompany that dissatisfaction," he wrote.
Mr Robinson's News Letter article also said unionists may have to decide between opposing the protocol or collapsing the Stormont Assembly.
Current First Minister and DUP leader Arlene Foster this afternoon said she hoped the Irish and British governments and EU take note of the unionist frustration highlighted by Mr Robinson.
She said people right across the unionist community are "very angry" about the protocol and the way in which the Good Friday Agreement has been interpreted by the Irish Government, Brussels and London.
Mrs Foster said the agreement has three parts - the parties in Northern Ireland, the North/South dimension and the East/West dimension.
"Once you start damaging one of those strands of the Belfast Agreement, then it does have an impact on the overall operation and I have been saying that for some time," she said.
"People need to take heed of what is being said by the unionist community and I hope that the message is being heard in London, Dublin and Brussels because we need to deal with this issue quickly."
Speaking in Fermanagh, she said any obstacle to the movement of people and goods between Northern Ireland and Great Britain undermines the Good Friday Agreement.
"I am really concerned about where the unionist community is a present," she said. "The Belfast Agreement is about consensus. There is not one unionist politician that thinks this protocol should stay."
A petition by the DUP to trigger Article 16 of the Northern Ireland Protocol is to be debated at Westminster on 22 February. It has gained almost 140,000 signatures so far.
Earlier, Mrs Foster said that trade problems created by the protocol need permanent solutions, not sticking plasters.
She restated her demand for the protocol to be ditched after the UK and EU reiterated their "full commitment" to the new arrangements.
"Northern Ireland needs freed from the Protocol," she tweeted. "We must have unfettered trade between GB & NI.
"It's time for the Government to step up & protect this part of the United Kingdom with permanent solutions, not sticking plasters. EU must recognise the absence of unionist support."
In contrast, Stormont's Deputy First Minister and Sinn Féin's leader in Northern Ireland Michelle O'Neill welcomed the EU-GB statement of its commitment to the Good Friday Agreement and implementation of the protocol.
I welcome EU/BG statement & commitment to GFA & implementation of Protocol, protecting the gains of peace, and avoiding hard border in Ireland. Engagement with businesses and civic society critical. I have been calling for Joint Committee to meet and glad it will meet by 24 Feb— Michelle O'Neill (@moneillsf) February 11, 2021
Minister for Foreign Affairs Simon Coveney described yesterday's EU-UK meeting as a "good day's work" and said the focus was now on co-operation between the EU and UK to implement the protocol.
"We continue to listen and do what we can to support businesses in NI," he said on Twitter.