Pakistan's Health Minister said nearly 700 people, most of them children, have tested HIV positive in a city in the country's south.

Authorities say the HIV outbreak in Rato Dero city started when local doctor Muzaffar Ghangharo, who has AIDS, infected patients in early April.

Ghangharo was arrested this month after hundreds of people tested positive for the virus. Police were investigating whether Ghangharo knowingly spread the disease to others.

"Some 681 people, of which 537 were children from two to 12 years of age, had been tested positive for HIV until yesterday in Rato Dero," Health Minister Zafar Mirza told a press conference in the capital Islamabad on May 26.

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He said 21,375 people had been screened in Rato Dero, adding that the increase in the number of patients testing positive for HIV was "a matter of grave concern." Mirza said one cause that was being investigated was the use of unsterilized syringes.

"Initial investigations reveal that used syringes are being repacked, which may not only grow significantly the number of HIV cases but also other diseases," he said. Pakistan has registered over 23,000 HIV cases nationwide. (RFERL)