Boris Johnson has insisted he wants to negotiate a solution to the post-Brexit issues affecting Northern Ireland, but said overriding parts of his deal with the EU would be “perfectly legitimate”.

The Prime Minister insisted solving the problems with Brussels “still seems possible”, but said the UK could trigger Article 16 of the Northern Ireland Protocol “reasonably and appropriately”.

European Commission vice-president Maros Sefcovic said on Monday that if the British Government suspended the protocol, it would have “serious consequences” for the region and Brussels’ relationship with the UK.

During a speech to business leaders and diplomats at the Lord Mayor’s Banquet in London, Mr Johnson said: “Let me say – given all the speculation – that we would rather find a negotiated solution to the problems created by the Northern Ireland Protocol – and that still seems possible.

“But if we do invoke Article 16 – which by the way is a perfectly legitimate part of that protocol – we will do so reasonably and appropriately, because we believe it is the only way left to protect the territorial integrity of our country, and meet our obligations to the people of Northern Ireland under the Belfast (Good Friday) Agreement.”

Earlier, No 10 said there were still “significant gaps” between the two sides and that the conditions to invoke Article 16 – which would in effect suspend elements of the arrangements that prevent a hard border in Ireland – had been met.

The Prime Minister’s official spokesman would not put a deadline on how long talks would continue, but said: “We are going to be continuing talks, intensified talks, between the two teams to try and find a consensual solution.”

He added: “I wouldn’t seek to put a time limit on it. I think the most important thing is to not place a time limit on it which could hinder potential progress.”

Speaking to Irish politicians, Mr Sefcovic said he would not speculate on whether the UK will trigger Article 16.

“However, it is clear that if they were to do so, the EU would have to consider all tools at our disposal,” he added.

“It would also have serious consequences for Northern Ireland and for our relationship with UK.”