Most of the drugs involved - methotrexate and cytarabin hydrochloride - have been recovered and authorities have traced the remainder, the Xinhua News Agency said. The report did not say if any of the drugs had been exported.
Authorities have banned the sale and distribution of the drugs, produced by the Shanghai Hualian Pharmaceutical Co., it said.
China, a major global supplier, has been facing growing international pressure to improve the quality of its exports after dangerous toxins - from lead to an antifreeze ingredient - were found in goods including toys and toothpaste.
China has been eager to cast itself as a victim, too, of unsafe imports. Xinhua on Saturday announced that inspectors recently found residue of the banned stimulant ractopamine in frozen pig kidneys imported from the United States and frozen pork spareribs from Canada. The names of the exporting companies were not identified. Ractopamine is forbidden for use as veterinary medicine in China.
Xinhua said the 18.37 tons of frozen pork kidneys and 24 tons of frozen pork had been returned to importers exporters, said the General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ).
Ractopamine, a hormone that promotes the growth of lean meat in pigs and cattle, is banned by China and most other countries as a health hazard, although its use in stock animals is permitted in the U.S. and 바카라사이트
Canada. China has also recently banned imports of U.S. meat contaminated with salmonella, additives, and veterinary drugs.
Xinhua said the State Food and Drug Administration and Health Ministry banned the two leukemia drugs after several child leukemia patients who were taking them complained of leg pains and difficulty walking. Xinhua said some patients also complained of urine retention.
It said the Health Ministry and drug administration had traced the problems with the drugs to their being tainted with vincristine sulfate, an anticancer drug. Xinhua said factories manufacturing the drugs had been closed.
China has taken a series of steps to crackdown on tainted drugs and other unsafe products, in part due to concern over the reputation of its exports.
In the harshest action
so far, the country's former top drug regulator was executed in July for taking millions of dollars in bribes to approve substandard medicines, including an antibiotic that killed at least 10 people.