Taoiseach Micheal Martin said the UK and EU need to “knuckle down” and resolve the dispute over Northern Ireland’s post-Brexit arrangements.

Brexit Minister Lord Frost will hold further talks with European Commission vice-president Maros Sefcovic on Friday, with the UK still warning that it could unilaterally suspend parts of the Northern Ireland deal unless major changes are made.

But Irish premier Mr Martin said he was encouraged that progress is being made and the “mood music” has changed.

In a BBC interview, Mr Martin cautioned the UK against taking the step of triggering Article 16 of the Northern Ireland Protocol, the step which would suspend parts of the arrangements.

The protocol was put in place to prevent a hard border with Ireland by effectively keeping Northern Ireland in the EU’s single market for goods, but that meant checks on products crossing the Irish Sea from Great Britain.

Mr Martin said the European Commission had put forward a “comprehensive package of measures” to address the concerns raised about the protocol, adding that some EU members thought Mr Sefcovic had gone “too far” in the concessions he had offered to reduce checks.

He said he believed serious talks were taking place between the UK and EU and “where there is a will, there is a way, and I think both sides just need to knuckle down and get it resolved”.

Negotiations on the Brexit trade deal a year ago stretched until December 24 and Mr Martin said “don’t leave it to Christmas Eve this year”.

Asked whether he could trust Boris Johnson, the Taoiseach said “I get on well with Boris Johnson on a personal level”.

On Thursday, Lord Frost told peers that the option of using Article 16 remained on the table despite speculation a deal was within reach.

Mr Martin said “my own view is that unilateralism never works” and using Article 16 would have a “very negative” impact.

In Parliament, Lord Frost said Brussels should not interpret his “reasonable tone” in talks to imply any softening of the UK’s position.

He told the House of Lords: “Whatever messages to the contrary the EU think they have heard or read, our position has not changed.

“We would prefer to reach a negotiated agreement if we can. That is the best way forward for the stability and the prosperity of Northern Ireland.

“But I want to be clear, I would not recommend any outcome from the negotiations that I did not believe safeguarded political, economic or social stability in Northern Ireland.

“In such circumstances, we would obviously need to provide the necessary safeguards using Article 16 and those safeguards are very much on the table and they are a legitimate provision in the protocol.”