In a statement on its website, China's General Administration of Quality Supervision, Inspection and Quarantine said the companies broke regulations by adding the melamine, and then broke the law by mislabelling the exported products to avoid detection.
 
Standards
 
Announcing the new regulations China's cabinet, the State Council, said on Wednesday the crackdown would compel companies to adopt "standards used in food-importing countries".
 
The Xinhua New Agency meanwhile cited officials as saying the government was in the process of drafting amendments to the country's food safety law, but gave no details.
 
It said all classes of food and drugs would be subject to more rigorous inspections, with an emphasis on securing the food supply chain and boosting food safety in the vast, mostly impoverished countryside.
 
The crackdown comes as China faces criticism from the US and European Union for what they allege are unfair trade practices, and fears that tainted food scandals could lead to bans on Chinese food products.
 
Banned

US inspectors say tainted pet food killed an
unknown number of dogs and cats [Reuters]
Already this year, the US states of Mississippi and Alabama have banned catfish from China after tests found they contained antibiotics banned in the US.
 
Excessive antibiotic or pesticide residues have also led to bans in Europe and Japan on Chinese shrimp, honey and other products.
 
Hong Kong blocked imports of turbot last year after inspectors found traces of malachite green - a potential cancer-causing chemical used to treat fungal infections - in some fish.
 
Within China meanwhile, babies have died after being fed fake baby formula, cancer-causing dyes have been injected into eggs to make yolks redder, and children have been given saltwater passed off as rabies vaccine.
 
At the same time, observers say, the Chinese agency that sets regulator standards for food and drug safety has been in disarray for years.
 
Its director, Zheng Xiaoyu, was sacked in 2005 and has since been accused of taking up to $780,000 in bribes to approve untested medicines, including an antibiotic that killed at least 10 patients.
 
He is scheduled to go on trial in mid-May on charges of corruption.