The PLA was committing over 180 divers to the search and rescue efforts, a commander told China Central Television.

The first batch of 13 divers sent to search for survivors said it had been very difficult to open the ship's doors underwater, especially given the poor visibility caused by the downpour.

Fourteen survivors are accounted for, authorities said Tuesday. 

The Ministry of Transport said in a statement on Wednesday that it has ordered checks to be carried out on vessels of the same type run by the Eastern Star's operator.

Some 109 ships and more than 1,900 people were involved in the rescue operation, the ministry said. 

Satellite data released by the China Transport Telecommunication and Information Centre showed the ship had made a 108-degree turn at about 9.20pm. It then travelled for a further 10 minutes before capsizing.

The ship had been carrying 405 passengers, 46 crew members and five tour guides, the youngest of whom was only three and the eldest over 80, according to a list of passengers obtained by the mainland media.

Zhang Hui, a tour guide from a Shanghai-based tour agency that was a major organiser of the trip, was one of 15 known to have survived.

The ship was sailing through a thunderstorm when it suddenly tilted at an angle of more than 45 degrees, he told the state-run Xinhua news agency.

"I tried to tell my colleague that we were in big trouble. But before I was able to finish the sentence, the ship had capsized," he said.

He managed to grab a life jacket and climbed out of the window of his bedroom, which had filled with water up to his neck.

The 43-year-old, who did not know how to swim, floated in the stormy waters for the whole night before tides pushed him to the shore at dawn.

Not until Zhang was found by local residents did he realise he had floated some 90km to Yueyang county in neighbouring Hunan province.

One of those saved by the rescuers was a 65-year-old female passenger. She appeared to be frightened but conscious as she lifted her blanket and looked around as she was rushed to the ambulance.

Deng Zhibo, deputy chairman of a local hospital, said three survivors had been taken to hospital with minor injures including dislocations.

The cause of the sinking was not immediately clear, but the captain, who was rescued and then held in custody together with the chief engineer of the ship, told local newspaper the the ship tilted towards its right side after encountering a tornado.

The ship capsized within one minute, he said.

The meteorological administration confirmed that the Jianli section of the river had recorded a tornado that lasted for 15 to 20 minutes.

The nearest weather station, 35km away, recorded winds of up to 16.4 metres per second at the time of the accident.

Initial investigations found the ship, which is capable of carrying up to 534 people, was not overloaded and that it had enough life vests on board for the number of passengers it was carrying, state media said.

The captain of another passenger ship that left port at around the same time as the Eastern Star on Monday pulled over temporarily at Chibi as the weather deteriorated, but the Eastern Star continued in an effort to arrive in Jingzhou by yesterday afternoon, the said.

Relatives of the missing have arrived at the scene of the disaster, waiting for news, the China News Service reported.

Family members arrived in two separate buses on Wednesday morning, organised by a travel agency that sold cruise tickets to many on board. 

Some stood on the river bank praying for the safe return of their loved one, the report said. 

The heavy rain is expected to continue until Friday morning.

In the worst previous incident of its kind in China, the steamship Kiangya blew up on the Huangpu river in 1948, killing more than 1,000 people.