The resurfacing of melamine-tainted dairy products in central China has triggered alarm once again over food safety in the aftermath of the 2008 dairy scandal that rocked China's dairy industry.

Last week, market regulators in Xiangfan, in the central province of Hubei, asked local businesses to trace 50 packages of corn-flavored dairy drink that are believed to contain melamine, a toxic chemical normally used in manufacturing plastics. Each package contained 15 bottles.

Sample tests showed the melamine level in the beverage measured as high as 4.8 milligram (mg) per kg, suggesting that the chemical was deliberately added during the production process to fabricate higher protein content.

Further investigations indicated that the drink was produced in a dairy firm in the southern neighboring Hunan Province. Earlier this year, Xiangtan Yuanshan Dairy Industry Company, the producer, bought a 25kg bag of Dongyuan-branded milk powder, along with 2kg samples, from its long-term supplier as raw material for the dairy beverage.

The producer did not conduct a check over the milk powder as the raw material supplier had offered all required quality reports. However, a test conducted by the Hunan administration of quality supervision and inspection showed that the melamine content was as high as 68mg per kg, far exceeding the national standard.

Moreover, after a thorough probe by the quality watchdog, the quality reports provided by the supplier were proved to be fabricated.

In July this year, the Dongyuan-brand of milk powder, produced in west China's Qinghai Province, was exposed for containing excessive levels of melamine. The dairy company, Xiangtan Yuanshan, claimed that it bought the raw material without knowing it was tainted with melamine.

However, in a July inspection by the local food safety watchdog, the company concealed the fact that it was using milk powder to produce dairy beverages.

Production in Xiangtan Yuanshan has since been halted and a local food safety watchdog has placed the case on file for further investigation and prosecution. The dairy firm is likely to face legal charges for breaking food safety laws, the local administration of quality supervision and inspection said on Tuesday.

More yet to come?

This latest revelation in Hunan Province added to a spate of discoveries of melamine-tainted dairy earlier this year. In March, several Shanghai company executives were held responsible for the chemical misuse and sentenced to jail terms.

In July, police arrested four suspects who allegedly added melamine to milk formula and seized 76 tonnes of tainted milk powder and dairy products in northwest China' s Gansu and Qinghai provinces in a crackdown on food safety crimes. Dairy products tainted with melamine were also found in Jilin and Zhejiang provinces.

Tainted dairy products resurfaced despite the Chinese government stepping up their efforts in cracking down on food safety crimes since the Sanlu scandal in 2008 that resulted in the deaths of six infants and sickening 300,000 children across the country.

In September, the Chinese government called for an oversight of sales of melamine and dairy firms were required to keep records of all raw materials purchased. In the meantime, dairy firms were required to conduct melamine tests on all products before putting them on the market.

The re-emergence of tainted dairy products again sent chills through Chinese parents. Some have chosen to purchase imported milk formula ever since the 2008 dairy scandal.