Five people have been arrested in Dublin, Belgium and Holland and up to 50kg of heroin has been seized as part of an Irish-led drug traffiking investigation.
An Irish plane has been impounded in Belgium following the operation, which was carried out by the Garda National Drugs Unit and UK police.
The plane, a private jet, flew out of Weston airport in Co Kildare to pick up a man at Kortrijk-Wevelgem airport, in southern Belgium, yesterday morning.
The pilot, the co-pilot and the 36-year-old passenger were arrested after the passenger tried to board the aircraft with the heroin packed in his luggage. The heroin is thought to be worth up to €10 million.
Officers from the Garda National Drugs Unit believe the drugs were destined for two Dublin-based criminal gangs.
Gardaí later searched at least five homes in Dublin, seized over €40,000 in cash and arrested a 27-year-old man who is being questioned in Clondalkin.
A fifth man, who is originally from Scotland, has been arrested in Holland.
Gardaí believe he was responsible for a number of substantial drug shipments to Ireland in the past few years.
Jet is owned by Mansfield
Businessman Jim Mansfield has confirmed that he owns the airplane which is being detained in Belgium.
A spokesman for Mr Mansfield said the flight was operated by the National Flight Centre, which is owned by Captain Kieran O'Connor and based at Weston Executive Airport.
Weston airport is owned by Mr Mansfield. It has no permanent customs presence and only 16 inbound flights from Europe were inspected last year.
A statement issued on Mr Mansfield's behalf said that the plane was being used by an aircraft operator whose own aircraft was unserviceable.
It is owned by Longborough Aviation, which is one of Mr Mansfield's companies.
The spokesman said Mr Mansfield was shocked by the development and the National Flight Centre is co-operating fully with the authorities.