Shanghai police said on Wednesday they detained five people in an investigation into a Chinese-based supplier of foreign fast-food brands, including KFC, McDonald's Corp and coffee chain Starbucks Corp , over allegations the firm supplied old and rotten meat.

The five detained include the head of the company - Shanghai Husi Food Co Ltd, a unit of US-based OSI Group LLC - and the firm's quality manager, the police said in an online statement.

McDonald's and Yum Brands Inc, the parent company of KFC and Pizza Hut, and a number of other global brands have pulled products from their outlets after it emerged that Shanghai Husi supplied expired meat to clients in China, as well as Japan.

Earlier, the official Xinhua news agency cited the Shanghai food and drug watchdog as saying that food safety violations at Shanghai Husi were company-led rather than the acts of individuals. "We discovered that some of the company's illegal behaviour was not the behaviour of individuals, but rather an organised arrangement by the company," Xinhua cited Gu Zhenhua, deputy head of the Shanghai Municipal Food and Drug Administration, as saying.

In a separate statement, the Shanghai food watchdog said it sealed more than 1,000 tonnes of suspected meat products from OSI in China, and a further 100 tonnes of products from a range of its customers.

Illinois-based OSI has said it was "appalled" and was investigating the matter after a Chinese TV report on Sunday showed staff at its Shanghai Husi facility using expired meat and picking up meat from the floor to add to the mix.

An official at OSI in China reached by telephone on Wednesday declined to comment further.A factory worker at another of OSI's food processing plants in the northern Chinese province of Hebei said on Wednesday that regulations were very strict at the plant, that all workers needed to wear special clothes, and that spot checks were often held unannounced,"The inspections are done by everyone: our own company, the government and also clients like McDonald's. Our rules are very strict and food safety standards are very high," said the worker, surnamed Wei, as he took a break at a nearby supermarket.

He added that the Hebei factory, which processes meat, vegetables and flour products according to its website, was still open for business despite government inspections.