BEIJING - China still faces a problem with the illegal sale of blood to hospitals, the Health Ministry said on Thursday, years after such trade sparked an AIDS outbreak in the central province of Henan.

China has promoted voluntary blood donations for decades and while they fulfill 95 percent of needs, the system had developed unevenly, the ministry said in a statement on its Web site (www.moh.gov.cn).

"The phenomenon in some areas of paying for blood supplies, or making money from blood, still exists, and there are hidden dangers for blood safety," it said.

The government would carry out a probe this year to "strike hard" against such practices, and try to better promote voluntary blood donations, the ministry said.

"We must earnestly deal with problems when they happen, solve them as fast as possible and come to a conclusion in a timely way," it added.

Hundreds of thousands of farmers in Henan were infected in the 1990s through schemes in which people sold blood to unsanitary health clinics, and dozens were infected with the deadly virus as a result.

Authorities have moved to clean up the country's blood collecting centers in recent years, but underground blood selling has persisted.