Chinese consumers have another thing to be concerned about when they do their grocery shopping - rat meat has reportedly been passed as fake lamb, according to the country's health officials who discovered the cover up.

The Ministry of Public Security released results of a three-month crackdown on food safety violators, saying in a statement that authorities investigated more than 380 cases and arrested 904 suspects since the end of January for selling tainted meat products, state-run news agency Xinhua reported. A total of 20,000 tons tainted product has been confiscated.

Despite an ongoing crackdown, "food safety crimes are still prominent, and new situations are emerging with new characteristics," the ministry's statement said.

Food safety is a major issue in China, where public anxiety over cases of fake or toxic food can spread quickly. Earlier this year, 20,000 dead pigs were found floating down the Huangpu River, a main source of water for Shanghai. That was followed by thousands of dead ducks in the Nanhe River in the southwest province of Sichuan. There was also a high-profile scandal involving the use of melamine in baby milk formula in 2008.