Three patients at hospitals in Tuscany were mistakenly given organs from an HIV-positive donor, raising serious concerns about transplant procedures in Italy.

A 41-year-old woman's kidneys and liver were taken after she died of a brain hemorrhage at Florence's Careggi hospital and were implanted due "to a tragic human error," the hospital said in a statement Monday. The director of the regional transplants agency said the patients' chances of infection are high.

The HIV test on the organs had come back positive, but "unfortunately the expert who did the report wrote down 'negative' for all the tests, including this one," said Careggi director Mauro Marabini.The three patients have been told of the mistake and will undergo tests to determine if they have been infected with the virus that causes AIDS. The three were receiving anti-retroviral drugs.

"They asked immediately if the transplanted organ was working, and it was working perfectly," Marabini said. "They reacted quite calmly."

Franco Filipponi, director of the regional transplant agency, told the news agency ANSA that the likelihood of infection is high. "Even if the implanted organs do not carry blood the virus can still be present in some cells and can therefore be transmitted," he said.

Prosecutors in Florence opened an investigation, ANSA reported.

Health Minister Livia Turco pledged to improve safety measures once the inquiry was completed, but stressed that the transplant system has saved many lives. "I cannot hide my preoccupation for an excessive alarm that could reduce trust in this system and slow the growth of donations, leading to further damage for other patients," Turco said.

Italy's public health system is not new to scandal. Last month, authorities ordered nationwide inspections after a magazine report on Rome's largest hospital showed images of corridors soiled with dog feces and garbage, unguarded radioactive material, abandoned medical records and workers smoking next to patients.

Police found that about 17 percent of hospitals, mostly in southern and central Italy, had problems serious enough to recommend possible judicial investigations against 111 people.