China has launched nationwide checks for melamine-tainted milk products after the industrial compound, which killed at least six children in 2008, reappeared on shop shelves, an official newspaper said on Tuesday.

Leftovers of milk powder laced with melamine, which can give a fake positive on protein tests, have been reused as raw materials for dairy products despite an earlier crackdown, the People's Daily said, citing a conference held by the State Food and Drug Administration.

Batches of dairy products made by three Chinese companies were forced off market shelves in the southwestern province of Guizhou last month after testing positive for melamine.

Tainted milk products were found in several provinces in 2009, from the northeastern province of Liaoning to the economic hub Shanghai, the newspaper said.

"In spite of the current campaign for food safety, some enterprise and individuals are still blinded by greed, ignoring the health and safety of the public," it said.

There have been no reported deaths or illnesses from the latest batches of tainted milk which can cause kidney stones in children and made 300,000 children sick in the 2008 scandal.

China executed two people in November for their role in the melamine scandal that further sullied the made-in-China brand after a string of health and product-safety scares.