Chinese police have arrested six suspects and detained 41 others who allegedly participated in distributing melamine-contaminated milk after a national crackdown in 2008, food safety authorities said Friday.

The latest melamine-tainted milk powder was first discovered in northwest China's Gansu Province, and police traced the source to the Dongyuan Dairy Factory in Minhe County of neighboring Qinghai Province.

The factory's chief, Liu Zhanfeng, deputy chief Liu Xiping, and workshop director Wang Haifeng were among those arrested, said an official with the National Food Safety Regulating Work Office.

Dai Wenming, chairman of Luyuan Dairy Company of Zhangbei County, Hebei Province, was suspected in having hidden 48 tonnes of milk powder tainted with melamine, a toxic chemical, which was supposed to have been destroyed after the 2008 scandal, and then sold it to the Dongyuan Dairy Factory through Sun Xuefeng and Zhou Zhonglin, who were also arrested.

Forty-one others have been detained after a series of cases with excessive levels of melamine in milk powder, such as that found in the milk powder of the Tianqing brand produced in northeast China's Heilongjiang Province.

In the 2008 scandal, unscrupulous Chinese milk producers were found to have been mixing melamine to dairy products in a bid to falsify protein content tests. The practice, said to have been long standing, caused the deaths of at least six Chinese babies and left anther 300,000 ill, sending chills to consumers at home and abroad.