Some eight of the 21 bodies had tabs with clinic code numbers attached to their feet. The tabs showed the bodies were from the hospital of Jining Medical University.
Local health authorities and police have launched an investigation into the dumping.
"The hospital medical staff involved have been suspended from their work during the investigation," said Zhong Haitao, a spokesman at the Jining Health Bureau.
Zhong said the 21 bodies were salvaged by local residents and firemen Monday after they were discovered under a bridge spanning the Guangfu River in the outskirts of Jining.
The Beijing News reported Tuesday the bodies may have been dumped by cleaners from local hospitals after abortions and induced labor. Such dead bodies are treated as "medical waste" by hospitals.
The municipal environmental department said the most recent tests on the river's water quality showed it was not contaminated with major water indicators, unchanged with that of 2009.
The river is not one of the city's drinking water sources.
Editor: Lin Zhi