The sets for the company's winter production of La traviata were being delivered from Germany's Theatre Aachen, which is co-producing the staging. Customs officials found the drugs, worth a half-million euros, while checking the shipment at Dover.
Rehearsals of La traviata, which were to start this week at the Gaiety Theatre in Dublin, have been delayed.
David Collopy, the company's CEO, said, "I am sure U.K. customs and excise along with the Gardai [Irish police force] and Belgian police can source where the drugs came from and release the shipment of costumes so there are no further delays to us going ahead with our winter production."
To Reuters, Collopy said, "This is not our doing, believe me. We don't know how the drugs got in there."