MANILA - The Philippines has declared a health emergency amid growing anxiety that a deadly coronavirus is already spreading undetected in the capital Manila and in nearby suburbs.

"The outbreak… constitutes an emergency that threatens national security, which requires a whole-of-government approach," President Rodrigo Duterte said in a proclamation released early on Monday (March 9).

The country later announced 10 more confirmed cases, bringing the total to 20.

On Saturday, the Health Ministry raised its alert to "code red sub level 1", the second-highest level, after confirming that the Philippines was now seeing local transmission.

Hours later, it disclosed that four more patients at hospitals in Manila were suffering from Covid-19, the disease caused by the virus.

"This is a pre-emptive call to ensure that national and local governments and public and private healthcare providers are prepared for a possible increase in suspected and confirmed cases," Health Secretary Francisco Duque had told reporters on Saturday.

"Moving from localised transmission to sustained community transmission can happen very quickly," he said on Monday, shortly after the health emergency was declared.

The health emergency releases funds to help local governments prepare for a massive community spread.

It also eases rules on the procurement of testing kits, masks, protective gear and other resources public health workers may need to combat the virus.

The government currently has only 4,500 testing kits. It expects 2,000 more from the World Health Organisation, and is also entertaining offers from China and South Korea.

Dr Duque said the perception among politicians that the Health Ministry was not doing enough "is largely because of our limited testing supplies".

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"As soon as we get more, then we will be able to expand our coverage of who will be tested," he said.

He said if the situation escalates and the country faces multiple community spreads, the government will raise its alert to "code red sub level 2", the highest level.

That will allow it to quarantine or place under lockdown entire communities, and suspend school and work.

He said this could be implemented at the municipal, city or provincial level,with the help of police and soldiers.

But he insisted that a lockdown was "premature".

"We have to wait for evidence of sustained community transmission," he said.

In a sign of growing unease, local governments have been taking ad hoc measures to assure communities they are ready to deal with a viral spread.

Three cities and two towns suspended classes this week so classrooms could be disinfected.

One town has distributed face masks, disinfectants and vitamins in neighbourhoods near the home of a 62-year-old Filipino who tested positive for the coronavirus.

The Muslim prayer hall that he frequented was ordered shut by the city mayor with jurisdiction over it.

Shopping malls have begun disinfecting their premises.

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Hospitals and affected companies have also been making their own announcements to dispel rumours and misinformation spreading online.

The 62-year-old was the Philippines' first case of community transmission. His 59-year-old wife has also been infected. Both have not been outside the Philippines recently.

On Saturday, the Health Ministry said that two more Filipinos, a Taiwanese and an American had also tested positive, which brought the total number of confirmed cases to 10.

Among these was a Chinese national from Wuhan who travelled to the Philippines and later died. This was the first death from the outbreak reported outside China.

Two patients - both Chinese - have recovered. Those still infected are currently warded in state-run hospitals with facilities for dealing with epidemics.