Cannabis plants worth £200,000 have been seized in Newry by detectives investigating an international drugs trafficking operation.
Cash was seized and a 32-year-old man was arrested.
As part of the investigation a 53-year-old man was arrested in south Belfast.
A 40-year-old man arrested earlier on Thursday in Belfast remains in custody.
Two men have also been arrested in Newry and Belfast.
In the past week detectives have seized £1 million worth of cannabis in Northern Ireland and made seven arrests.
Police said this is in addition to £1.2 million worth of skunk cannabis seized by police in recent months.
The investigation, in partnership with the National Crime Agency and Italian Carabinieri police, has also led to arrests and drugs seizures in