Three suspected smugglers were detained with a huge amount of shark oil from Cinema Palace area of Chattogram city on Sunday.
The detainees were identified as Rashed, 32, Kazu Sohel, 32, and Md Sagar, 27.
ASP Mahmudul Hasan Mamun, media officer of Rab-7, said they detained the trio from a mini-truck when they set up a check-post in the area early hours of the day.
Later, Rab members recovered 3,600 litres of shark oil from their possession and seized the truck.
The recovered oil is worth Tk 21.6 lakh, he added.