Each of these two ships can lift only 60 tons and together they can rescue vessels weighing up to 120 tons. Most big launches plying the major routes weigh close to 1,000 tons.

Moreover, lack of modern equipment delay rescue work, officials said.

Rustam was bought in 1983 and Hamza in 1966.

"Our passenger vessels even weigh up to 1000 tons. We don't have the capacity to salvage them. We also do not have proper equipment to run smooth rescue operation," Syed Aminur Rahman, senior deputy director of Bangladesh Inland Water Transport Authority, told The Daily Star during the rescue operation of MV Lighting Sun that sank in Meghna Sunday.

During the salvation of the 80-ton Lighting Sun, this correspondent found the officials of Rustam merely trying to recover the dead with only two divers and seven labours. After working continuously for five to six hours, the rescue team became too exhausted and stopped work.

The steel cables tied to the sunken vessel snapped at least four times. The ship was only 12 feet into the water.

When another launch MV Nasrin sank last year, the rescue team could not even detect the ship under water. Later, a navy team came and detected the vessel.

Officials said the rescue ships do not have cutting and welding machines necessary for rescue operation.

In the recent case of Lighting Sun, rescue operation was stalled for six hours due to lack of a welding machine to seal the bottom of the launch that was cut open to rescue seven persons alive.

"We do not have proper diving equipment and sonar machine to detect sunken vessels," Md Mounddin Haider, commander of Rustam, said.

Bangladesh has 7,000 kilometre of river routes during the monsoon, which shrinks to 5,000 kilometre in dry season.

Some 7,000 registered river vessels -- 2,000 passenger launches and 5,000 cargo vessels -- ply these routes.