Fourteen people were arrested on Thursday morning as armed police, some of them hooded, swooped on a garage at Triq il-Vittmi tal-Gwerra in Birkirkara.
The arrested persons are between 23 and 66 years old and include Maltese, Italian, British and Serb nationals.
The police said they found sachets which they suspect contained heroin, as well as other drug-related items and cash.
Investigations are continuing and a magisterial inquiry is being held.