Gardaí are reportedly investigating whether smugglers may be using Ireland's small airports to get drugs into the country.
The inquiries follow the seizure of 50kgs of heroin yesterday at an airport in southern Belgium.
The drugs, worth an estimated €10m, were found in the luggage of a man who was boarding a private plane based at Weston Aerodrome in Dublin.
Reports this morning say the Gardaí believe other small Irish airports are being used to bring in drug shipments because of the lack of customs checks.
A review of security at these airports will reportedly be carried out in the wake of yesterday's operation, which was led by the Garda National Drugs Unit.
Five people are still in custody as a result of the sting. Three were arrested at the airport in Belgium, another near Weston Aerodrome and the fifth in the Netherlands.