Speaking to reporters, the PM said he is "really committed to resolving some of the issues with the protocol" amid the ongoing impasse in Northern Ireland.

"I have not put a strict deadline on the talks (between the government and the EU) and I don't want to raise people's expectations of an imminent breakthrough," he said.

"What I can tell you is I am very committed to resolving this issue.

"The foreign secretary met with his counterpart just this week, talks are ongoing, and I will work as hard and as fast as I can to find a resolution to the issues with the protocol.

"I want to do that as soon as practically possible."

Labour win Stretford and Urmston by-election - politics latest

Mr Sunak said he is "not going to give a running commentary on the negotiations", adding: "What is of paramount importance to me is protecting Northern Ireland's place in the union.

"The protocol, clearly there are areas of it which threaten that.

"I want to resolve those and I want to protect Northern Ireland's place in the union.

"That is what I am setting out to do. If we can do that, we can get the executive up and running, that is what people need and deserve."

Westminster and Brussels continue to negotiate over the Northern Ireland Protocol, which was introduced after Brexit to avoid a hard border between Ireland and Northern Ireland.

However, it has effectively placed a border in the Irish Sea as Northern Ireland has to stick to some EU import/export rules, while goods moving from Great Britain to Northern Ireland are subject to a tariff if they are "at risk" of being moved into the EU afterward.

In May, Sinn Fein made history by becoming the first nationalist party to win the most seats in Northern Ireland Assembly elections, with the unionist DUP experiencing big losses.

The protocol is being blamed for much of that turnaround in votes, with the DUP refusing to take part in government unless the protocol is abandoned or replaced.

Read more: What is the Northern Ireland Protocol?

Ministers in Westminster have now put forward a bill that allows it to change the protocol without the permission of the EU.

But the EU has threatened the UK with legal action if it does so.

Arriving in Northern Ireland yesterday, the PM held informal talks with senior representatives of the main parties at a hotel near Belfast.

He met all the parties in the same room and spoke to them separately for around 10 to 15 minutes each.

Both DUP leader Sir Jeffrey Donaldson and Sinn Fein vice president Michelle O'Neill - who is in line to become first minister of Northern Ireland if devolution is restored - were present.

Read more: Sunak and von der Leyen promise to 'work together' to solve NI Protocol row

Earlier, the local political leaders met with Northern Ireland Secretary Chris Heaton-Harris for cross-party talks in Belfast.

One key issue that featured in the discussions in Belfast on Thursday morning was the continued uncertainty over when £600 Treasury-funded energy support payments will be rolled out to householders in Northern Ireland.

Mr Sunak confirmed to reporters on Friday that the UK government would be making an announcement on the payments "very soon".

Last week, Mr Heaton-Harris cut the pay of MLAs by 27.5% to reflect the fact they are not doing their jobs as legislators.

If a new executive is not formed by January 19, the UK government assumes a legal responsibility to call a snap assembly election by April 13.