All dairy products made before Sept 14 must be pulled off the shelves to be tested for melamine, a chemical blamed for killing¹ four babies and sickening more than 54,000, according to a government notice made public Tuesday.

"Regardless of the brand or the batch², all products made before that date must be taken off shelves and their sale must be stopped," said the notice jointly³ issued over the weekend by six central government departments including the Ministry⁴ of Health and the General Administration of Quality Supervision⁵, Inspection⁶ and Quarantine (AQSIQ).

The AQSIQ press office told China Daily Tuesday the cut-off date was set for Sept 14 because the central government already requires every batch of dairy products made after that date to undergo melamine checks before entering the market.

The notice said the pre-Sept 14 products could be sold again only after they pass quality tests and are labeled as safe.

It is the first time that the government has issued a blanket recall of products since the contamination scandal broke on Sept 11, and the aim, the notice said, is to "ensure all products on the market are safe for consumption".

Baby formula products must be sent to testing centers designated by provincial⁷ quality control departments, while tests on other products such as powdered milk for adults and liquid milk can be conducted by other testing agencies or the manufacturers themselves, the notice said.

The AQSIQ also announced Tuesday that the latest round of tests on 154 batches⁸ from 51 brands of powdered milk products, including infant formula, show them to be safe for melamine content. Melamine is often used in plastics but is banned in the food industry. It can make milk appear high in protein in quality tests, but can cause kidney problems if consumed.

The AQSIQ said tests have shown all powdered and liquid milk products made after Sept 14 are safe.

About 100 of 756 batches of powdered milk products and 24 of 1,202 batches of liquid milk made prior to that were found contaminated.

As a result of the notice, few liquid milk products made before Sept 14 were being sold in Beijing Tuesday.

"All liquid milk products made before Sept 14 have been pulled off our shelves," Chen Ran, a sales manager of the Wu-Mart branch in Chaoyang district, said.

Zhang Yongjun, another sales manager of the branch, said sales of dairy products had dropped by two-thirds in the first few days after the scandal broke, but customers were recently beginning to buy them again.

Meanwhile, some media organizations have reported that parents of at least two babies who died after being fed tainted⁹ milk food had filed compensation lawsuits¹⁰ against the manufacturers.

However, lawyers have suggested that judicial¹¹ departments consider class action lawsuits because of the huge number of victims involved.

"Individual lawsuits can achieve justice for some, but more will choose to give up because of high costs or other reasons," Liu Junhai, a law professor at Renmin University of China, was quoted by Nanfang Weekend as saying.

"Individual lawsuits will also waste judicial resources and may take a long time to resolve."