China's state-run Xinhua news agency reported Saturday that the 30-meter (98-feet) vessel had had 25 people on board, including eight foreign nationals, when it sank on Thursday.
Rescuers dragged the 368-tonne ship Saturday to shallow water before searching it for those still unaccounted for.
Three people, all Chinese, were rescued, with one person still missing as authorities continue to search the vessel's cockpit and nearby areas of the Yangtze River in the Jiangsu province, Xinhua reported.
The newly built, Wanshenzhou 67, was making its maiden test voyage Thursday in the Fubei Channel when it capsized.
Sembcorp Marine Ltd, a Singapore-based shipbuilder, said Friday the tugboat sank during a sea trial. The ship's owner, parts suppliers and engineers were among those on board.
Rapid currents hampered the rescue effort, and it was not until Saturday morning when rescue teams were able to surface the vessel and tow it to shallow waters to undertake a more thorough search.
jlw/sb (AP, Reuters)