At least 11 workers have died in an explosion on a disused oil tanker in the Bangladeshi port city of Chittagong.

Police and fire fighters said some 40 workers were also badly injured.

Police recovered some charred bodies from the big oil tanker that was in the country's largest ship-breaking yard along the Bay of Bengal.

Police say the explosion might have been caused by gas trapped inside a pipe in the ship.

A wounded worker told BBC that he suddenly heard a big bang, saw black smoke and fell down.

He was rescued later along with some others by the fire brigade and sent to hospital.

Trapped

Police say that they are still searching for other people, who may have been trapped inside the vessel.

Rescue officials at the scene were unable to say how many people were working in the ship when the accident took place.

Ship-breaking industry is a major source of steel for the country.

It also employs thousand of workers and it has been alleged that most of them work without the necessary protection.

An injured worker alleged that explosions often occur while breaking ships, but most them go unnoticed.

Pollution

Apart from such risks, old ships often cause environmental pollution by spilling oil into the Bay of Bengal.

The government, in association with the World Bank and the United Nations Development Programme (UNDP), launched a project today to prepare guidelines for environment management by the ship-breaking industry along with 17 other industries.

The guidelines are expected to be prepared within two years.