Boris Johnson has insisted there must be unionist consent for the Northern Ireland Protocol as he warned it was not working as he had envisaged.

The Prime Minister was said to be in “listening mode” as he visited Belfast and Arlene Foster’s constituency of Fermanagh for a series of engagements on Friday, before later holding crunch talks with the First Minister and her deputy, Lord Dodds.

However, he came under renewed pressure from Mrs Foster to tear up the “intolerable” protocol governing post-Brexit trade between Britain and Northern Ireland, which has been blamed for causing major disruption due to added red tape and checks.

Mrs Foster also used the visit to highlight to Mr Johnson the practical implications on the ground, pointing out that a local school in her constituency had been unable to import trees from England due to EU rules surrounding the transport of soil.

The decision to hold talks with the DUP was criticised by Sinn Fein’s vice president Michelle O’Neill, who snubbed an invitation to meet Mr Johnson on the grounds that the party had not received a response to a request to hold their own discussions.

Separately, Lord Frost, the minister in charge of EU relations, on Friday insisted that a historic drop in trade flows between the EU and UK in January had been due to a “unique combination” of factors, including stockpiling and covid-19.

It came after new figures from the Office for National Statistics showed a 41 per cent drop in UK exports to the bloc in the first month after the end of the transition period, alongside a 28 per cent drop in EU imports.

It represented the largest decline in exports and imports with the EU since comparable records began in 1997, although Lord Frost insisted that Brexit and covid stockpiling, as well as lockdowns across Europe, had contributed to the decline.

The Government also claimed that freight volumes had returned to normal in February.

Last week the UK chose to unilaterally extend grace periods for supermarkets and parcel couriers operating in Northern Ireland, while also relaxing requirements on a series of other goods, including those relating to soil movements.

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The EU claims that the move breached the protocol, which is overseen by the two sides jointly, and is now preparing to launch legal action in retaliation.

However, Mrs Foster and other unionists parties, who want to overhaul the protocol completely, say that the temporary measures do not go far enough to prevent the creeping dislocation of Northern Ireland from the rest of the UK.

Speaking afterwards, Mr Johnson said there was a need for “symmetry and balance” to post-Brexit trade in Northern Ireland, adding that unionists as well as nationalists – who favour the protocol because it ensures closer ties with the Republic of Ireland – needed to be able to support it.

“There has got to be east-west consent to what is going on, as well as north-south. We want to make sure that is built into that.”

Defending the Government’s decision to act unilaterally last week, Mr Johnson later told a regional press conference said that the new border checks required under the protocol were not being carried out in the way he intended.

“It needs to be corrected, you can’t have a situation in which soil or parcels or tractors with mud on their tyres or whatever are prevented from moving easily from one part of the UK to another – it’s all one United Kingdom,” he added.

“What I didn’t want to see was loads of checks on stuff going from GB to NI in such a way as to interrupt trade and to confuse and irritate people.

“I didn’t want to see barriers to the circulation of sausages and tractors with mud on their tyres and all the rest of it, and nor did I think that would be necessary and I think that’s why we put in the easements we have, because I think it’s sensible for there to be some balance in this and I think there’s a commonsensical way forward and that’s what we want to have.”

Meanwhile, the DUP leader in Westminster has welcomed the idea of the House of Commons briefly sitting each year in the devolved nations, requesting that Northern Ireland is the first to benefit.

The proposal – an attempt to strengthen ties across the UK – is being pushed by Jacob Rees-Mogg, the House of Commons leader. It was first reported by The Daily Telegraph.

Sir Jeffrey Donaldson, the MP for Lagan Valley, said the proposal for MPs to sit occasionally in Stormont, Holyrood and the Welsh Parliament was “terrific” and “wonderful”.