"Illegal blood collection still exists in some blood stations and even medical institutions. There is no strict mechanism to ensure the safety of blood sources," said Vice-Minister of Health Ma Xiaowei.

China claims 20 percent of its estimated 840,000 HIV/AIDS patients got the disease from selling plasma, although international experts believe the total number of cases and people infected through blood sales is far higher.

The China News Service said China has shut down 49 blood collection and provision institutions in a recent campaign to curb the practice in the central province of Henan, the worst affected from the blood-selling scandal.

It said 35 serious cases of illegal blood collection were under investigation, and 19 suspects had been arrested.

Meanwhile, 42 blood collection stations and medical services have received "severe punishment" for illegal blood deals, the agency reported without giving details.

The campaign has also examined blood products of 24 companies with three ordered to halt production, it said.

According to the Henan government, most of the 14,505 HIV carriers in the province became infected after selling blood in the 1990s to a group of illegal blood stations which used unsanitised instruments.

Until recently, China denied it had a serious AIDS problem but national leaders have begun acknowledging that urgent action was needed to curb the spread of the deadly disease.

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