Detective Police arrested six alleged drug peddlers from the city's Khilgaon area with 5,008 bottles of phensedyl in their possessions on Friday.
Senior Assistant Commissioner of Detective Branch (DB) of police Moshiur Rahman said they had got information that a gang will bring two consignments of phensedyl to the city from Shatkhira, Benapole and Jessore.
On Friday, a team of DB took position under the Khilgaon Flyover and stopped a private car around 11:00pm.
Labu Gazi, 41, Gazi Salauddin Khokon, 30, and Ayesha, 30, were arrested from the car with 2,603 bottles of phensedyl.
Later, according to their confessions, the police halted the second car in the same place and seized 2,405 bottles of phensedyl from Amir Hamza, 57, Mahfuzur Rahman, 28, and Sagar Talukder, 23.
The arrestees used to sell drugs to some retailers at different parts of the city, said the police.
Police were trying to arrest the retailers.