Chinese officials have canceled 621 food production licenses from 564 producers in an ongoing campaign to improve food safety, the country's top quality watchdog said in a statement posted on its website yesterday.

The General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ) said 355 food makers failed to renew licenses after relocation, restructuring, or their licenses expired.

The AQSIQ cancelled licenses in another 249 food companies because they went bankrupt or stopped production.

Production licenses in 17 firms were canceled as their production conditions failed to meet official standards and the remaining three were revoked for severe offences.

The AQSIQ said the measure was a renewed effort to boost safety supervision and ensure food safety.

Food safety has become a major public concern in China since a spate of food scares from parasite-infested snails to ducks and hens that were fed cancer-causing Sudan Red dye to make their egg yolks red.

To allay concern, the government has taken a series of measures, including a recall system for unsafe food and clamping down on the illegal use of toxic pesticides and animal feed additives nationwide.