Local police detained the men, named as Julian Steele and James Davis, along with two Afghan colleagues in the capital Kabul on Tuesday.
Afghan officials said they were found to be transporting 30 AK-47s with their serial numbers scratched off and did not have the necessary firearms permits. The case has been sent to Afghanistan’s attorney-general for further investigation.
Private security firm GardaWorld, which employs the four people under arrest, said the men were taking the guns to a firing range for testing before they purchased and properly licensed them.
The Canada-based company said in a statement: “We fully comply with all laws and regulations in our Afghanistan operations and are making every effort to work closely with the Afghan authorities to rectify the situation as soon as possible.”