MANILA - The Philippines has reported its first case of a Filipino who has not been out of the country getting infected with the new coronavirus now sweeping much of the world, fuelling worries of a massive community spread that may be going undetected.

The patient is a 62-year-old man in San Juan city, just east of the capital Manila.

"The patient sought medical consultation at a Manila hospital on March 1, and was admitted with severe pneumonia. A specimen collected on March 4 tested positive for Covid-19 on March 5," Health Secretary Francisco Duque told reporters on Friday (March 6).

The man was known to frequent a Muslim prayer hall in San Juan, and was reported to be a stall owner at a popular shopping mall in the city.

The city's mayor Francis Zamora has ordered the prayer hall closed and disinfected.

Dr Duque said that while this was the Philippines' "first local case", it did not yet suggest a "local transmission".

"There's no transmission to speak of as of yet because we only have one case. We have to establish whether there are other cases or clustering of cases. It's premature to say we have a local transmission," he said.

When asked how the patient got the virus, Dr Duque replied: "We really don't know. That's the reason we're doing contact tracing to find out the source, if at all possible."

Dr Rabindra Abeyasinghe, the World Health Organisation's Philippine representative, said while the case suggested a local transmission, "we are not sure whether we are looking at a local case or a cluster of cases".

He also sought to play down fears of a massive community spread.

"A cluster of cases doesn't mean that you are having widespread local transmission We don't talk of community transmission till we clearly know the extent of the cluster," he said.

Dr Duque said it was "premature" to raise the alert level to "code red".

"The evidence points to only one case… But as soon as we do get confirmation, or once we get more positive confirmed cases, then that's the time we can say there is a local transmission, and the door for intervention, which we have been preparing for anyway, will have to be actually (opened)," he said.

But Senator Risa Hontiveros, a rights activist, said the new case "is a cause for concern and a wake-up call for our health officials".

"We should not give the public a false sense of security because the danger of local transmission is real," she said.

The country's only confirmed cases of Covid-19, the disease caused by the coronavirus, had up to this point involved three Chinese nationals from Wuhan, where the virus originated.

On Friday, health officials disclosed that three others - from Taiwan, Japan and Australia - who had been to the Philippines recently, tested positive for the virus shortly after they returned home.

A 48-year-old Filipino lawyer who travelled frequently to Japan has also tested positive for the virus. He lives in Manila, and is currently warded at the Research Institute for Tropical Medicine.

Dozens more Filipinos are infected, but they are all abroad, with three of them in Singapore.