Scores of divers searched a capsized ship in the Yangtze River on Wednesday for more than 400 missing people, many of them elderly tourists, as the death toll in what could be China's worst shipping disaster in almost 70 years jumped to 18.

State television showed rescuers, some standing on the upturned hull of the Eastern Star cruise ship, working through the night. So far their efforts have yielded few successes, with only 14 people found alive, including the ship's captain.

Also among the few rescued was an elderly woman, who had been trapped in an air pocket in the ship, which capsized during a freak tornado on the river on Monday night.

Search area expanded

The Yangtze search area has been expanded up to 220 km downstream, state television said, suggesting that many bodies could have been swept far away from where the ship foundered in the rain-swollen river.

Zhang Hui, a tour guide, who survived the disaster, told Xinhua that it was raining so hard water was seeping through cabin windows, and that the ship then listed violently.

"I thought, 'this isn't right', and I told my colleague, 'I think we're in trouble'. After I said that, the ship flipped over. It only took 30 seconds or a minute," Mr. Zhang said.

Relatives protest

The ship's captain and the chief engineer have been detained by police for questioning. An initial investigation found the ship was not overloaded and had enough life vests on board.

The ship overturned "within one or two minutes", Xinhua quoted the captain as saying. He was dragged out of the water near a pier just before midnight on Monday.

Relatives of the missing, angry at what they perceive as a lack of information, have scuffled with officials in Shanghai. All of the passengers on board had booked their trips through a Shanghai-based travel agency.

Early on Wednesday, about two dozen family members, some crying and others shouting "help us", marched down streets in central Shanghai towards the main government office watched by a heavy police presence.

A passenger manifest carried by state media showed those on board the Eastern Star ranged in age from three to more than 80. There were 456 people on board when the ship capsized.

Premier Li Keqiang, who rushed to the scene to oversee rescue efforts, called for "regular and transparent updates" on the rescue and investigation, and said authorities must ensure adequate personnel and funding.