A 29-year-old man from Co Down has been arrested on suspicion of importing 13 firearms into Northern Ireland through the post.
The man was arrested at a property in Bangor on Wednesday by National Crime Agency officers, along with the PSNI.
They said the 13 weapons were believed to be “forward venting blank firearms” but were readily convertible to fire live rounds.
NCA officers said they suspect the weapons were purchased online and mailed to the Bangor address.
Officers also recovered two air rifles, an array of weapons including pepper sprays, machetes, knives and knuckle dusters, and half a kilo of cannabis.
The arrested man remains in custody and is now being questioned.
The NCA’s David Cunningham said: “This type of firearm can be converted into a lethal weapon, and then used by organised criminals to threaten, intimidate, and kill.
“We are investigating whether these weapons were being imported with the intention of them being sold on the criminal market.
“Working with our colleagues at the PSNI we are determined to do all we can to disrupt the flow of illegal firearms and keep them off the streets of Northern Ireland.
“Criminals smuggling these weapons should know we and our policing partners will pursue them tirelessly.”
Project Vizardlike is a national NCA-led operation targeting people buying forward venting blank firing weapons online and importing them into the UK.
Since 2018, more than 550 prohibited weapons and 3500 rounds of ammunition have been seized in the UK by the NCA and police forces as part of this project, with almost a hundred arrests made.
Anyone with information is advised to report it to police or anonymously to Crimestoppers on 0800 555 111.