The pacts covered cooperation in many fields, including investment, taxation, maritime transport, labour, and education
Police said two others have been injured in the accident on the Bagerhat-Mawa Highway at Fakirhat Upazila on Monday.
The deceased, who are yet to be identified, include two minors, a female and a male, said local highway police's Sub-Inspector Md Jamal Hossain.
He said a head-on collision occurred between the Dhaka-bound bus and battery-run three-wheeler around 10am. "The four victims died on the spot."
Two others have been taken to the state-run hospital in Fakirhat Upazila town, added the police officer.