Rescue workers are seen at the site after a tug boat sank in the Yangtze River, near Jingjiang, Jiangsu province, January 16, 2015. REUTERS/China Daily

Twenty-one people have been confirmed dead and one person is still missing, after a tugboat capsized on China's Yangtze river Thursday, according to a report from the country's state-run news agency Xinhua.

The vessel capsized in the Fubei channel of the river in the eastern province of Jiangsu, and was carrying 25 people, including eight foreigners when it overturned. Three people have been rescued alive, including a man who rescuers cut through the hull of the upturned vessel to release, according to the Associated Press.

Rescue workers were able to right the boat in the early hours of Saturday, almost 40 hours after it capsized. Around 30 vessels had been dispatched to hunt for survivors, but rescue efforts were hampered by low temperatures and a strong current, Xinhua reported.

It added that in addition to Chinese, there were four Singaporeans, an Indian, a Malaysian, an Indonesian and a Japanese onboard at the time of the accident.

One of the survivors, Wang Chenhua, who said that he had been acting as an interpreter for the Japanese engineer on board, said that soon after they had conducted a load test for the boat's main engine, the boat "suddenly turned over," and water rushed in, flooding the cockpit "within 20 seconds." He survived by holding onto a hydraulic pump that was not submerged, according to the BBC.

The vessel, a tugboat which had been newly built, was undergoing testing when the incident occurred.

One person is still unaccounted for. "As long as we have the slimmest hope, we will give a 100-percent effort," Wang Shiming, deputy head of the Jiangsu Maritime Safety Administration, said, according to AFP.