BEIJING — Chinese parents were in an uproar on Monday after reports that hundreds of thousands of children might have been injected with faulty vaccines, the latest scandal to hit the nation’s troubled drug industry.

The outcry came after a government investigation and news reports showed that a major drug producer in northeast China, Changchun Changsheng, had violated standards in making at least 250,000 doses of vaccine for diphtheria, tetanus and whooping cough.

While there have been no reports of deaths or illnesses related to the substandard vaccines, the news has rattled public confidence in the government and rekindled fears that corruption and abuse in the nation’s vast pharmaceutical industry are placing people at risk. It has also undermined President Xi Jinping’s efforts to restore faith in medicine produced in China at a time when the country is striving to become a leading producer of pharmaceuticals.

After a series of scandals involving tainted food and drugs in China, many parents said they were fed up and called on the government to take more severe action.