Public concern over quality control at a pharmaceutical company in East China's Jiangsu province has widened from the rabies vaccine to the A/H1N1 vaccine.

The Hongkong-based Mingpao reported on Tuesday that the Ealong biotech company, located in Changzhou, used an "additive" when producing a rabies vaccine, which may affect more than 1 million people nationwide.

The substance reportedly allows vaccines produced by the company to meet inspection standards at a lower cost, while compromising the drug's potency. The adulteration was allegedly used in more than half of its vaccine products in recent years.

The Ealong biotech company admitted on Thursday that quality defects had been detected in four batches of rabies vaccine last December and that production had already been suspended.

The company denied a media report that the rabies vaccine it produced in 2008 may affect more than 1 million Chinese people. It did not comment on the "additive" reportedly used in the vaccine.

The investigation into the vaccine is ongoing, said Yan Jiangying, a spokeswoman for the State Food and Drug Administration, who refused to give any further information.

Seven top executives from the company have reportedly been arrested on suspicion of producing and selling defective drugs, though local police authorities declined to confirm the arrests.

The Ealong biotech company, which is controlled by the New York-listed Simcere Pharmaceutical Group, produced about 11 percent of the nation's rabies vaccines in 2008.

The company is also one of eight domestic pharmaceutical manufacturers authorized to produce the A/H1N1 vaccine and reportedly produced 6.31 million doses of it last year.

Up to now, no adverse reactions to the rabies vaccine have been reported, but a woman from Yancheng, Jiangsu province, has claimed there was a connection between her daughter's death one month ago and the A/H1N1 vaccine produced by the company, the Hunan-based Xiaoxiang Morning Post reported on Thursday.

You Zhihua, 40, said her daughter was the victim of the A/H1N1 vaccine produced by the Ealong biotech company, reports said.

You's daughter Fei Jingming, who was a high school student, was injected with the A/H1N1 vaccine on Nov 17, 2009.

"Five days later, my child began to show symptoms of a cold and on Nov 23 she ran a fever. She didn't recover after receiving a transfusion and taking pills in the school's hospital. Meanwhile, I found some hemorrhage points on her legs and there were some blood blisters in her mouth," You was quoted as saying.

On Dec 6, Fei's oral blood blisters became enlarged and her eyeballs started to bleed. Fei was soon sent to hospital and was diagnosed with acute aplastic anemia. On March 8, the girl died.

You said local disease control authorities and the health bureau said the A/H1N1 vaccine would not lead to acute aplastic anemia, but You did not accept the result, reports said.

The medical certification states that the A/H1N1 vaccine injected into Fei was produced by the Jiangsu Ealong biotech company, with the batch number 200909L13.