The latest tests on Chinese milk powder have found no traces of melamine, the country's top quality control agency said yesterday.

It was the third round of tests for the industrial chemical since the the breaking of the tainted baby formula scandal that left at least three infants dead and sickened more than 50,000 others, according to the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ).

The tests covered 113 batches of baby formula from 20 brands in nine provinces and 267 batches of other milk powder from 72 brands in 18 provinces, the agency said.

At present, 460 batches of baby formula from 50 brands and 576 batches of other milk powder from 133 brands produced after Sept. 14 have been tested and none contained melamine, it added.

Melamine, often used in the manufacturing of plastics, was added to sub-standard or diluted milk to make the protein levels appear higher.

The Ministry of Commerce on Friday said it hoped other countries would treat Chinese dairy products fairly and set up no barriers to normal trade activities.

The AQSIQ has started strict quality checks of dairy exports, the ministry said. Dairy exports after Sept. 10 were safe.

The State Council, or Cabinet, issued a series of quality control regulations for dairy products on Thursday.

The regulations tighten control of how milk-yielding animals are bred, how raw milk is purchased and the production and sales of dairy food.

They promised more severe punishment for people who violated safety standards and quality control departments that failed to fulfil their duties.