Relatives of more than 400 people missing from a cruise ship which capsized in central China clashed with police on Wednesday as hope that survivors would be found turned to anger at a lack of new information.

Just 14 people have been rescued from the "Eastern Star" which overturned late Monday in a storm leaving only a section of its hull emerging from the Yangtze river, state-media said.

While 26 bodies have been found so far, according to state broadcaster CCTV, hundreds of mostly elderly passengers are still missing and feared possibly trapped within the ship.

Witnesses and state-media said the cruiseliner -- which was carrying a total of 456 people, most aged over 60 on a holiday cruise -- sank in a matter of seconds after it was hit by bad weather.

Around 20 bodies appeared to have been found on Wednesday as rescue efforts continued more than 40 hours after the accident, with dozens of divers searching each of the ship's rooms one by one, CCTV said.

Fields around the site of the capsized boat were heavily waterlogged and many of the pathways being used by rescue workers were ankle-deep in mud and rainwater.

A transport ministry spokesman told AFP that rescuers were facing low visibility in the muddy waters, but would keep searching even as hopes of finding survivors dwindled.

"We will never give up our last efforts," Xu Chengguang said.

Information on the disaster has been tightly controlled and officials gave little away during a news conference on Wednesday afternoon, providing no figures on deaths or survivors and taking no questions.

Anger at the lack of news boiled over outside local government building in China's commercial hub of Shanghai, where many of the passengers hailed from, where a video shared on social media showed pushing and shoving between police and angry relatives.

"The police first formed a human wall and didn't let us in. Then the relatives got excited and started to shout. Some policemen hit people," said one young woman whose mother was on the boat.

The mother of seven-year-old Yang Chenlin who was on the boat with her grandparents, said relatives were desperate for more information. "We need to go to the site. That's our common appeal," she said.

At the Jianli County People's Hospital, frantic relatives arrived searching for missing loved ones.

"We drove from 10 pm last night to 6 am this morning to get here," a woman who looked pale and warn told AFP at the hospital, adding that her uncle and aunt had been on board.

"We don't really know anything," said a man who had travelled with her.

Hospital officials by late Wednesday had sealed off the facility from reporters, along with a local funeral parlour.

China tightly controls its domestic media and a government directive posted online by the US-based China Digital Times said local outlets had been ordered to only use reports from state-media.

Roadblocks were sited about two kilometres (1.2 miles) from the capsized vessel, with cars being turned back even before that point. Authorities also limited access for foreign journalists to a brief river trip.

At the site of the disaster, CCTV images showed grim images of what appeared to be a dead woman being pulled from the water, her body already rigid.

Later, the channel showed China's Premier Li Keqiang bowing to bodies covered in white sheets as rain poured down.

CCTV said the 250-foot (76.5-metre) vessel had floated three kilometres down river after it capsized in Jianli county, part of the central province of Hubei.

Passengers seemed to have little warning before the ship sank, with Zhang Hui, a 43-year-old tour guide on board, telling Xinhua that he had "30 seconds to grab a life jacket".

The captain and chief engineer, who were among the survivors and were being questioned by police, both reportedly said the ship was caught in a freak storm.

The ship was cited for safety infractions two years ago along with five other vessels, according to a notice by the Nanjing Maritime Bureau, which gave no details on why the boat was detained or subsequent actions taken.

Condolences for the disaster came from the United States, European Union, the UN and the Vatican.

"I wish to express my closeness to the Chinese people in these difficult moments after the ferry disaster in the Yangtze River," said Pope Francis.