An emergency meeting of the Stormont Executive to discuss implications of a new more aggressive variant of Covid-19 is taking place tonight.
Senior Executive Sources told RTÉ News that First Minister Arlene Foster and Deputy First Minister Michelle O'Neill engaged in discussions with the British government to get answers to "critical questions".
They are now convening a remote meeting of Executive ministers and their chief medical and scientific advisors.
It comes after parties called for an urgent meeting to discuss the response to the new Covid-19 strain detected in parts of England.
No changes have been made to restrictions on family gatherings in Northern Ireland, but people have been urged to limit them to Christmas Day only.
This new more aggressive variant of Covid-19 has not yet been detected in the region, but health experts have said it is just a matter of time.
There is uncertainty about what the development means for people planning to travel home from England this week.
It comes as another 13 people with Covid-19 have died in Northern Ireland. A further 505 new cases of the virus have also been reported in the past 24 hours.
Yesterday, Ms Foster, Ms O'Neill and Mr Swann met chief medical officer Michael McBride and chief scientific adviser Professor Ian Young yesterday as rules were tightened in parts of the UK.
British Prime Minister Boris Johnson effectively cancelled Christmas for millions of people across London and south-east England after scientists said the new coronavirus variant was spreading more rapidly.
Ms O'Neill said: "Christmas bubbling arrangements are in place for those who feel they need to come together.
"If you must avail of them, then please consider doing so for one day only, Christmas Day.
"Keep your bubble as small as possible and meet for the shortest amount of time you can.
"We are clearly very worried about the Covid-19 situation that is unfolding. The speed at which this variant strain of the virus is spreading is deeply concerning."
Mrs Foster said: "Progression of a new variant strain of Covid-19 in England is concerning, and a reminder to us all to be on our guard to the dangers of the virus.
"The Executive has already taken significant action earlier this week in advance of other regions.
"It is incumbent on us all to do what we can to minimise the risks of Coronavirus spreading.
"We ask everyone to think carefully about all their actions and follow the public health advice rigorously."
The Northern Ireland Executive decided last week to impose a six-week lockdown from 26 December.
But, under current plans, up to three households will be allowed to congregate together in "social bubbles" between 23 and 27 December, unlike the rest of the UK.
The first week of the measures will see the toughest lockdown yet in Northern Ireland, with a form of curfew in operation from 8pm, shops closed from that time and all indoor and outdoor gatherings prohibited until 6am.
Additional reporting PA