China says 904 people have been arrested for selling fake, spoiled, or adulterated meat over three months.

State media portrayed the arrests on Thursday as part of a national crackdown that would now focus on dairy products, but an official told the state's Xinhua News Agency that there were deep-seated food safety problems which had not yet been solved.

Xinhua News Agency said suspects sold meat that had been injected with water to increase its weight, or sold rat and fox flesh as mutton.

"In Wuxi, in east China's Jiangsu Province, suspects made fake mutton from fox, mink and rat by adding chemicals," the news agency reported.

"The products were sold to markets and the suspects made more than 10 million yuan ($1.62 million) from the illegal activities."

According to an initial investigation, some of the suspects had used hydrogen peroxide solution to process chicken claws since July 2011. With an output of 300 kg per day, suspects made more than $650,000 in profits.

The news agency said that a total of 382 cases were uncovered and 20,000 tons of unsafe meat seized from January.

China's past food safety problems have included infant formula consisting of nothing more than starch and the recycling of household waste as cooking oil.