Police in north China's Hebei Province have detained 22 people involved in a network connected with making, selling melamine and tainting milk with the chemical.

Among the detained, 19 people were managers of 17 pastures, breeding farms and milk purchasing stations. The local procuratorate has issued arrest warrants for 13 of them, according to the investigation panel of the Sanlu Group tainted milk case.

More than 800 police staff conducted raids on 41 pastures, farms and milk purchasing stations in Shijiazhuang City, Hebei's capital, and seized 222.5 kg of melamine.

According to police investigation, melamine was produced in underground plants and then sold to breeding farms and purchasing stations.

One of the suspects, surnamed Gao, said he had been producing "protein powder" containing melamine in Dingxian County since late last year. A man surnamed Xue helped him sell the powder to purchasing stations.

Another suspect, surnamed Geng, ran a farm in Dingxian. He said his milk was always rejected by Sanlu for failing the company's test. He was told later that lacing the milk with a chemical (melamine) could increase the proportion of protein and pass the company's test. He then began tainting fresh milk with melamine.

Investigation into the case is still underway.

(Xinhua News Agency September 29, 2008)