Local courts in Shanxi and Hebei provinces in North China convicted and sentenced 14 people on Friday for producing or selling tainted milk powder.

Among the 14 involved in four tainted-milk cases, two received life imprisonment, four received sentences of 10 to 15 years in prison, while the rest received lighter sentences.

The Intermediate People's Court in Jinzhong city of Shanxi province sentenced Li Baosheng to life imprisonment, and confiscated all his personal properties, for blending melamine-tainted milk powder into his own products.

Qi Weigang, who sold Li 11.31 tons of melamine-tainted milk power, was also sentenced to life imprisonment.

By July 2010, authorities had seized a total of 173.17 tons of tainted milk powder produced by Li, worth 4.415 million yuan ($671,000).

The local court of Weichang county in Hebei sentenced Zhao Chunfeng, general manager of Yuquan Dairy Company in Chengde city of Hebei, to 15 years' imprisonment and fined him 1.37 million yuan, for selling the recalled tainted milk powder after changing its packaging and producing shoddy milk powder.

The court of Zhaoxian county in Hebei imposed a fine of 400,000 yuan on Yukang Dairy Company Ltd of Shijiazhuang city for concealing 30 tons of melamine-tainted milk powder during a government crackdown campaign and selling it in its products later.

Yang Hengzhu, the company's manager, was sentenced to six years in prison.

The open trials came three years after melamine-contaminated milk powder killed at least six babies and sickened 300,000 others across China.

Chinese leaders have recently called for stern punishments for those who produce or sell inferior products.