MANILA - The Philippines' sprawling capital will go through another round of hard, sweeping lockdowns to head off a deadly surge of the highly contagious Delta variant of the coronavirus.

Metro Manila will be under "enhanced community quarantine" (ECQ), which imposes the strictest lockdown measures, for two weeks from Aug 6, President Rodrigo Duterte's spokesman Harry Roque announced on Friday (July 30).

Metro Manila, which spans 16 cities, is home to some 13 million people, or about one-tenth of the country's population.

"This is a painful decision... but we need to do this to avoid a shortage of (intensive care) beds and other hospital requirements if cases balloon because of the Delta variant," said Mr Roque.

Health Undersecretary Maria Rosario Vergeire said the decision was in line with data modellers' forecasts that warn of a Delta-fuelled explosion of Covid-19 cases.

Experts from the independent group Octa Research this week warned of a "catastrophic surge" that could lead to "thousands dying", unless the government acted now. They recommended a two-week "hard and early circuit-breaker lockdown".

"We feel that a catastrophic surge, left unfettered, unabridged by a lack of government intervention, is a greater loss to all of us, loss of life and livelihoods," said Professor Ranjit Rye, a spokesman for Octa.

Metro Manila will be under strict shelter-at-home restrictions from Aug 6 to 20. Only those considered as essential workers and or who need groceries and vital supplies will be allowed to go out.

Police checkpoints may likely be put up again across the region. Restaurants and food outlets will be limited to take-out, while salons, barber shops and nail spas can fill up only one-third of their seats. Churches will be shut.

Malls will remain open, but only pharmacies and shops that provide groceries and home repair needs will be open.

Octa had warned that the Delta variant, first detected in India, could cause Covid-19 cases in Metro Manila to spike to more than 2,000 a day.

The government had been able to bring down infections in Metro Manila to below 1,000 a day after it imposed tougher quarantine curbs in March and April, when daily cases soared to more than 15,000 across the country.

It has so far avoided the crippling Delta-fuelled outbreaks that have plagued Indonesia, Malaysia, Vietnam and Myanmar.

But cases in Metro Manila have been creeping up in recent days to more than 1,000, with the Health Ministry finding clusters of Delta infections in a couple of cities in the region. This week, Delta cases have more than tripled.

The variant is also believed to be behind surges in cities where infections remain high despite tight quarantine curbs for weeks.

Dr Guido David, a senior research fellow at Octa, said a two-week ECQ should bring cases back down to about 600 a day.

The Philippines has the second-worst outbreak in South-east Asia, with close to 1.6 million Covid-19 cases. More than 27,000 have died.

Mr Duterte earlier this week said he was not inclined to fall back onto rolling lockdowns "lest our economy bleeds to the point of irreversible damage".

But if the Delta variant leads to the kind of deadly surge now plaguing Indonesia and Malaysia, he said, "you have to go back to lockdowns".

"If something wrong happens, I'll have to be strict, just like in the early days," he said.