BEIJING — China announced a complete overhaul of its dairy industry Thursday to improve safety at every step — from cow breeding to milk sales — saying its worst food quality scandal in years had revealed "major problems" in quality control.

Changes will be made within the next year in production, purchasing, processing and sales, the official Xinhua News Agency reported.

Milk and milk products tainted with melamine, an industrial chemical, have been blamed in the deaths of at least three infants and have sickened more than 50,000 others. The government has detained dozens of people in the scandal, but there have been no court cases so far.

The State Council, China's Cabinet, said the Health Ministry will issue new quality and safety standards for dairy products, while the Agriculture Ministry will draft inspection standards for melamine and other toxins in animal feed. The flow and delivery of dairy products also will be tracked, it said in a statement.

The breadth and speed of the proposed changes echo actions taken last year, when a slew of Chinese exports — from toothpaste to toys — were found to contain high levels of potentially deadly chemicals.

After an initial unwillingness to acknowledge problems, authorities threw themselves into a campaign to protect export industries and bolster the country's reputation as the world's manufacturing base.

The government formed a Cabinet-level panel to oversee product quality and food safety, implemented a national food recall system and announced increased random inspections.