Manila - Philippine health authorities on Monday confirmed the first cluster of swine flu cases in the country, where the total number of infections has risen to nearly 200.

Health Undersecretary Mario Villaverde said the source of the outbreak in Helera village in Jaen town, Nueva Ecija province, 90 kilometres north of Manila, has not yet been identified.

"It is still a big question mark," he said. "We are still trying to find the index case in Helera."

He added that the authorities were checking a number of possible sources, including a medical mission group from Manila that visited one week before the first case was reported.

Villaverde said 103 residents have manifested flu-like symptoms in Helera, and 20 have been confirmed to be H1N1 infections. Twelve of the confirmed cases are students at an elementary school.

Eric Tayag, chief epidemiologist of the Department of Health, said residents of nearby villages were also under observation for flu-like illnesses.

"We are monitoring 39 cases in Pakul village and 52 cases in Lambakin village," he said. "These two villages are adjacent to Helera and there are students in the Helera school who live there."

Tayag said the department had recorded a total of 193 confirmed cases of H1N1 infections throughout the Philippines.

Last week, the World Health Organization declared swine flu a pandemic after 74 countries reported nearly 30,000 cases, with 145 deaths since April.(dpa)