BEIJING, Feb. 21 -- Some 10,100 people have been prosecuted for production and sale of substandard and poisonous food between 2011 and 2013, China's Supreme People's Procuratorate (SPP) said here on Friday.

According to data from the SPP, prosecutors also approved the arrest of some 7,000 people linked to manufacture and marketing of food products.

Speaking at a press conference in Beijing, Nie Jianhua, SPP vice directorin charge of public prosecution, said illegal workshops, factories and markets were the major sources of problematic food.

Suspects were mainly self-employed business people, farmers or unemployed, he added.

Prosecutors also revealed at the press conference details of five criminal offences concerning food safety which, accroding to the SPP, were of "instructive" importance.

In one such case, a suspect named Liu Liguo sold 100 million yuan's worth of "gutter oil" made from kitchen waste between December 2007 and July 2011. Some 9 million yuan's worth of such unsafe oil entered the cooking oil market.

"Gutter oil" literally refers to recycled oil dredged from gutters behind restaurants as well as inedible animal oil. The oil, which contains carcinogenic substances, is dangerous if consumed.

Liu was given a life sentence in 2013.

In another case, Sai Yue and Han Chengwu, director and vice director of the Chongming county bureau of quality and technical supervision, were sentenced to six and two years and a half in prison for dereliction of duty and taking bribes after a food company in Chongming was found to have produced poisonous cooking oil.

Official dereliction and graft played a major role in food safety cases, said Guan Fujin, another vice director.

He said 531 officials had been investigated in 2013 over their involvement in cases concerning harmful medical and food products.