Police have seized a record $31m worth of amphetamine-like stimulants in Dubai, the local press said.
Dubai's police chief, Major General Khamis Mattar al-Mazeina, told the Khaleej Times newspaper that the operation, codenamed "nine ball," dealt a major blow to drug trafficking in the United Arab Emirates on Monday.
Five people of different Arab nationalities were implicated in the shipment of some 4.6m Captagon pills.
Captagon was originally the brand name for fenethylline, a synthetic stimulant.
The black market version of the drug has become popular in the Middle East and often contains amphetamines and caffeine, according to a 2011 UN Office on Drugs and Crime report.
So far three people have been arrested.