Shanghai food and drug administration has suspended the operation of a food company suspected of supplying stale meat to McDonald and KFC outlets.

Earlier on Sunday the administration had ordered that all meat products supplied by Shanghai Husi Food Co., Ltd should be taken off shelf for safety concerns.

Local media reported the company reprocessed meat products that had outlived their shelf life and supplied them to transnational fast-food chains including McDonald, KFC and Pizza Hut.

Reporters who managed to enter Husi workshops said they saw clear evidence that stale beef and chicken were repackaged after processing and their shelf life was prolonged for another year.

Investigators sent by Shanghai food and drug administration arrived at the company's facility in an industrial town in Jiading District at 7:30 p.m., but were stopped by security guards at the main entrance.

The two sides argued for more than an hour, until the investigators called police.

Shanghai Husi Food Co., Ltd, a member of the U.S. OSI Group, was a solely foreign-funded company with a registered capital of 50.47 million yuan.

In a "commitment to customers", posted at Husi's Shanghai plant, the company promised "hazard analysis and critical control points (HACCP)", a systematic preventive approach to food safety, and "routine sample microbe test".

Yang Liqun, general manager of deep processing with OSI China, said the company has a strict quality control system and will cooperate in the investigation.