BEIJING, Dec. 21 -- China's food and drug watchdog has urged supervisory bodies at various levels to tighten supervision of the distribution and sales of infant formula milk powder.

Food safety regulators have been asked to carry out strict checks and approval measures and enhance supervision on the qualifications of milk powder operators, according to a statement released by the China Food and Drug Administration.

Random inspection and risk monitoring of dairy producers should also be strengthened, the administration said.

The food safety committee under the State Council, China's cabinet, has urged dairy producers not to purchase fresh and raw milk from illegal operators and not to rush to buy sources of raw dairy materials.

The committee asked local food safety supervisory departments to detail their measures and ensure food safety during the upcoming New Year and Spring Festival holidays, adding that leading milk powder producers should take full responsibility for the safety work.

Public trust in domestic dairy companies was damaged in 2008, when melamine-tainted milk killed six infants and sickened thousands of others.

The reputation of foreign brands was also in question after some of the whey protein produced in May 2012 by New Zealand dairy giant Fonterra was found to be contaminated with toxic bacteria.