An overloaded ferry sank in rough conditions in central Bangladesh on Monday with up to 200 passengers on board, in the latest disaster to hit the country's rivers.

Emergency workers said around 100 survivors and two dead bodies had been pulled out of the river, but the rest remain unaccounted for.

"The waves were huge, the ferry was rolling heavily from side to side," said survivor Syed Saadi, whose wife and two sons were still missing.

"The boat flooded with water after a huge wave hit it, and tipped over before sinking under the water," he told Channel 24 television.

The ferry was around 30 kilometres (20 miles) south of the capital Dhaka when it sank on the river Padma in the central district of Munshiganj.

Ferry accidents are common in the impoverished country, with overcrowding and poor ship design and maintenance often to blame.

Local police chief Tofazzal Hossain told AFP the vessel was overloaded with passengers and conditions were rough.

Rescue workers and the navy have been mobilised at the scene and a ship with underwater cameras deployed to try to locate the sunken vessel.

Fire service official Mohammad Dulal told AFP that divers were being deployed to try to locate the sunken ferry and look for survivors. But stormy conditions and large waves were preventing them from going into the water.

- 'Huge waves' -

The police chief of Madaripur, where the ferry began its journey, said it was carrying between 170 and 200 passengers.

But one survivor, speaking on local television, said there were up to 350 passengers on board.

"There was no storm, but the weather was cloudy and the river was rough," he said.

"Suddenly the ferry was hit by a wave and flooded with water. I got out through a window and the ferry sank quickly.

"I was rescued by a local motor boat, other people were also rescued by boats."

Bangladeshi ferries do not maintain passenger logbooks, and are often overloaded.

Emergency workers at the scene said thousands of onlookers had gathered on the banks of the swollen river Padma.

Story continues

August is monsoon season in Bangladesh, when rivers run high, and the ship was completely submerged.

Bangladesh, one of Asia's poorest nations, is criss-crossed by more than 230 rivers and boats are the main form of travel, especially in the southern and northeastern regions.

However many of the vessels in use date back to before independence in 1971.

Officials have said more than 95 percent of Bangladesh's hundreds of thousands of small and medium-sized boats do not meet minimum safety regulations.

In May, a passenger ferry thought to be carrying between 150 and 200 people sank in central Bangladesh, killing dozens of people. The exact death toll remains unknown.

Survivors blamed the ship's captain for refusing to take shelter from a gathering storm.

Around 150 people were killed in the same district in March 2012 after an overcrowded ferry carrying about 200 passengers sank when it was hit by an oil barge in the middle of the night.