More than ten million illegal cigarettes have been seized at Belfast Port.
The haul, which represents around £5.3 million (€6.2m) in unpaid taxes, was seized by revenue and customs officers after being found inside a container.
No arrests have been made but an investigation is under way.
Lucie Irving, assistant director of the fraud investigation service at HM Revenue & Customs (HMRC), said tobacco fraud can be used as a resource for organised crime groups.
"Cheap cigarettes come at a cost as they often fund organised crime and other illegal activity that causes real harm to our communities, such as drugs, guns and human trafficking," she said.
"This is a huge seizure of illegal cigarettes and our streets would have been flooded with them had they not been discovered.
"We are determined to stamp out tobacco fraud by working closely with our partners in the UK and internationally to bring those responsible to justice."
Darren Brabon, assistant director of Border Force Northern Ireland Command, said the seizure of the cigarettes would help prevent harm to young people and the local community.
"Illicit cigarettes are dangerous, harmful and fund organised criminal gangs," he said.
"Children and young people are key targets for those who peddle illegal tobacco and cigarettes, encouraging them to take up smoking and exposing them to crime.
"This seizure is another example of our commitment with HMRC and partner agencies to stop these illicit items from entering the country and harming our communities."
The illicit tobacco market costs the UK around £2.5 billion (€3bn) per year.
