BEIJING (AP) ― Chinese courts have sentenced 14 people to prison for producing or selling melamine-tainted milk powder, news reports said Saturday, highlighting Beijing’s struggle to stamp out rampant sales of phony or tainted food and medicine.

Three years after use of melamine in infant formula killed six babies and prompted a shake-up of China’s dairy industry, authorities still are seizing tons of tainted milk. Adding melamine to watered-down milk can make it appear to have adequate protein.

In the latest cases, courts sentenced two people on Friday to life in prison, four to terms of 10 to 15 years and others to shorter terms, the official Xinhua News Agency said.

One who was sentenced to life in prison was a producer named Li Baosheng, who was accused of selling 130 tons of milk powder containing melamine, Xinhua said. It said authorities seized that and an additional 43 tons he had not sold yet.

The other who received a life sentence was identified as Qi Weigang, who was convicted of selling Li 11.3 tons of tainted milk powder. Xinhua gave no other details about Qi.

The sentences were imposed by courts in the northern provinces of Shanxi and Hebei, Xinhua said.

Zhao Chunfeng, general manager of the Yuquan Dairy Co. in Chengde, a city in Hebei, was sentenced to 15 years for selling tainted milk that had been recalled and producing shoddy milk powder, Xinhua said.

In 2008, nearly 300,000 children were sickened after consuming infant formula containing melamine, which can cause kidney damage. Dozens of people were arrested and a dairy farmer and a milk salesman were executed.

New cases of phony or tainted food or medicine are reported regularly despite repeated crackdowns and threats of severe penalties.

This year, authorities have uncovered sales of drug-tainted pork, bean sprouts treated with a carcinogenic chemical compound and old bread treated with sweeteners and dye to make it seem fresh.

The spate of problems prompted China’s Cabinet to order a renewed crackdown last week on illegal food additives.

A newspaper said this week that 26 tons of melamine-tainted milk powder was seized from an ice cream maker in the southwestern city of Chongqing. The report said the company bought the powder to make pastries and ice cream.