"They were infected by something dangerous that spread very quickly," Supari told a press conference after meeting officials of the World Health Organization. "We suspect that their deaths were most probably caused by bird flu."

She added that there was no evidence the three had contact with poultry, raising concerns of human-to-human transmission.

Iwan Siswara Rapei, 38, an official at the Supreme Audit Agency, 38, died Tuesday at a hospital in the town of Tangerang in Banten Province, three days after the death of his 1-year-old daughter Thalita Nurul Azizah. His other daughter Sabrina Nurul Aisyah, 9, died Thursday morning.

The three, who began to receive treatment at the end of June, fell ill after Rapei returned from an official assignment in Hungary.

Sardikin Giriputro, chief of a Health Ministry medical team, said Thursday the three died from acute cluster pneumonia and not bird flu.

Supari said no bird flu virus was found in the specimens of Rapei and his elder daughter in the initial test. There was no test for the other daughter as she had been buried before her samples were taken. The second test, however, indicated possible presence of bird flu virus.

"We have sent their specimens to a laboratory in Hong Kong to confirm the cause of their deaths and it can only be known within seven days," Supari said.

"As of July 14, the health condition of Mr. Rapei's wife, son and two housemaids is still good," she added.

Later, in an interview with the Jakarta-based private radio station Elshinta, Supari expressed hope that the deaths were not caused by other diseases even more dangerous than bird flu, but called on Indonesians not to panic.

The Jakarta-based private television network Metro TV reported that medical teams for various infectious diseases, including bird flu, SARS and diseases related to rats, have been sent to Rapei's house in a luxurious housing complex in Tangerang.

Health Ministry officials have ordered Rapei's neighbors to put mouse traps in and around their houses.

Last month, the Indonesian government announced the first bird flu case in Indonesia, saying a farm worker in South Sulawesi Province had been exposed to the bird flu virus but was not infected by it.

According to the latest data from the Agriculture Ministry, 16.2 million farm birds died of the virus in Indonesia last year.

From January to the middle of April this year, 449,452 birds died of avian flu in 13 regencies in the provinces of South Sulawesi, West Java, Central Java and East Java, the data showed.

Last month, the Agriculture Ministry confirmed that it had found a positive bird flu case in pigs in Banten Province in the western part of Java Island, raising concerns that the deadly virus has taken a step closer to infecting humans in Indonesia.

By Christine Tjandraningsih