Twenty-three people were still missing on Friday, a day after their ship hit a freighter and sank in the Yangtze River.

Officials with the Maritime Safety Bureau under the Ministry of Communications told reporters on Friday that rescue efforts were continuing at the site in Fuling District of Southwest China's Chongqing.

River tragedy: A woman stands by the Yangtze River bank crying for a member of her family involved in yesterday's collision between a passenger liner and a freighter near Fuling of Southwest China's Chongqing Municipality.

The collision occurred 30 kilometres upstream of the Three Gorges Reservoir.

Twelve survivors were found soon after the collision.

But rescuers have since searched waters for 3-to-4 square kilometres around the site where the ship sank without success. No bodies have been recovered, officials said.

The turbid waters of the river have added to the difficulties facing rescuers.

Local governments have organized 17 ships, including 11 fishing boats, to search for the missing passengers, said Chongqing Evening News. The Three Gorges Shipping Company which owned the ill-fated passenger liner has also sent fishing boats to the river's lower reaches.

Shu Chenglu, a doctor with Linshi Central Hospital of Chongqing, said his hospital had received nine survivors, ranging in age from 13 to 63 years.

All are in a stable condition, with most suffering only minor health problems, such as breathing difficulties and, in one case, injuries to the legs.

The patients have been given oxygen and are likely to leave the hospital in one or two days, said the doctor.

Of the 12 passengers saved, 11 were rescued by a fishing boat which was nearby when the collision happened, eyewitnesses and survivors said.

Survivor Zhang Wenjun told reporters the fog was so thick he could not see properly.

Zhang said he heard a big bang before the ship, called Fuzhou No 10, tilted and started taking water. It sank shortly afterwards.

The ship sank so quickly that only a few passengers were able to hang onto the wooden benches on board.

Zhang Qiuyue, a 15-year-old student with Fuling No 2 Middle School, told reporters she was lucky to be among those who found a handhold when the ship capsized.

Besides Zhang, two other people also grabbed hold of the same bench.

Zhang said her elder sister who was also on board was still missing.

Another survivor Zhao Dajun, who was also rescued by the fishermen, told reporters that his mother was yet to be found.

The youngest survivor of the accident is a pupil, who was travelling to Fuling to sit the middle school entrance exam the next day.

The ship's captain Liu Wanzhong, who had more than 20 years' experience on the water, was also missing, sources said.

The public security department has detained the freighter ship involved in the collision and its crew.

Local government sources said investigations into the accident are under way.

Chongqing's leaders rushed to the site to support and co-ordinate rescue efforts and help the survivors, according to China News Service.