A leading virologist has warned there is "a real risk" of the South African strain of Covid-19 spreading here.
Dr Connor Bamford, a research fellow at Queen's University, also expressed concern at evidence suggesting the current vaccines might be less effective against this strain.
Experts are seeking to urgently test 80,000 people in England for Covid-19 after it emerged the South African variant may have spread in some regions.
Health officials said 11 people had been identified over the last five or six days who have tested positive for the variant, but who have no links to travel.
This suggests there may be pockets of spread of the new variant in local communities, with the possibility of further cases.
Experts from Public Health England (PHE), who have been sequencing around 5% to 10% of all positive cases looking for variants, are now hoping to break any chains of transmission.
All but two areas involved single cases of the variant.
The South African strain is thought to be as transmissible as the variant that was first identified in Kent, but there is no evidence that it causes more severe disease.
It is not yet known whether the Oxford University/AstraZeneca vaccine will be effective against the variant, although other vaccines have shown promising results.
To date 105 cases of the South African variant have been identified in the UK since December 22, but all of those had links to travel.
Stormont's Department of Health said last night there had been no evidence to date of it circulating locally.
It added: "Intense work is continuing to identify any new variants which may emerge over time."
But Dr Bamford says the fact that there is community transmission within the UK immediately suggests there is a real risk of spread to here.
He said: "Given there are enhanced restrictions in the community already in place, this would mean that new variants would find it difficult to gain a foothold in Northern Ireland, but not find it impossible.
"There is therefore an argument supporting bolstering protection at our internal and international borders.
"There are numerous ways to defend against this variant (and others known and unknown), which include, first and foremost, enhanced testing and genetic surveillance, effective restrictions like social distancing and stricter protection of the border, like enhanced testing and enforced quarantine.
"What is also more concerning is the fact that we are identifying evidence of community transmission from weeks back within the UK that suggests we have not managed to block and capture those viruses incoming on international travel."
Experts believe the 11 new cases of the South African variant may have second or third generation links to travel.
However, detailed investigations have not identified any such links to date.
Mobile testing units and some home testing kits are being sent into the affected areas of London, the West Midlands, east of England, south east and the north west.
People will be urged to agree to testing, whether they have symptoms or not.