He said the cargo vessel involved in the collision had been seized.

"We are trying to locate the sunken ferry," Chowdhury said.

Boat and ferry accidents attributed to poor safety standards and overloading are common in Bangladesh, which is criss-crossed by a network of 230 rivers.

Officials said some of the passengers had boarded the launch on Thursday without buying tickets - something common across Bangladesh where many river accidents occur due to overloading and inexperience or negligence of the crew.