The Philippines now has all three variants of the coronavirus that have been fuelling record-breaking spikes in infections across the globe, as well as a Philippine variant that has the same lineage as the infectious Brazilian variant.

This comes as the country is seeing another surge in Covid-19 cases to levels not seen since the outbreak here peaked in the middle of last year.

The Health Ministry reported yesterday that it had detected the Brazilian variant in a Filipino who recently came back from Brazil. The strain had swept through Manaus city in the Brazilian state of Amazonas in November last year. No other details were released about the carrier.

This variant is believed to be fuelling a health crisis in Brazil and is now present in two dozen countries. It also has the ability to infect some people who had immunity from previous bouts of Covid-19.

The Philippines is already wrestling with two other variants - the British strain, as well as the South Africa strain that can dodge human antibodies, blunting the effectiveness of some vaccines.

There are currently 177 cases of the British variant and 90 cases of the South African variety in the Philippines.

A fourth variant that originated in the Philippines is also spreading. It was first identified in a Filipino who travelled to Japan. The so-called Philippine variant has the same lineage as the Brazilian strain.

Over 90 cases of this local strain are now being monitored.

Health officials said it is not yet a "variant of concern", though it manifests mutations that show it may be more transmissible than the original version of the coronavirus.

"We still lack evidence to determine if it will have significant public health implications," the Health Ministry said in a statement.

The Philippines is again tightening quarantine curbs after seeing a surge in infections in recent weeks, driven in part by the new variants.

A curfew from 10pm to 4am will be in place again starting tomorrow around Metro Manila, the capital region that is home to some 13 million.

Checkpoints are being set up in some districts to impose the curfew. Border controls across the region's 16 cities are also being readied. This may include reinstating travel passes.

"We're back to square one. We're not moving forward," said Senator Joel Villanueva.

The Philippines currently has the second-worst Covid-19 outbreak in South-east Asia, after Indonesia, with over 610,000 cases and more than 12,600 deaths.

The Health Ministry reported 5,000 new infections yesterday, the largest single-day surge since August. About half the total cases are in Metro Manila.

The country experienced a particularly worrying spike in infections in August. That was when it recorded its highest number of daily cases - 6,598.

Health workers at the time demanded a "timeout" to prevent the surge in infections from overwhelming hospitals. The government refused to reimpose a sweeping lockdown, but promised to tighten quarantine curbs

The current spike in cases comes as the government is moving to revive an economy that has been in recession since last year.

President Rodrigo Duterte said last week that he wants to reopen the economy with "a timetable of just weeks".

"We cannot forever be (under) strict protocols," he said.

The Philippines has started inoculating its population of over 100 million. But with a global supply squeeze, only about one million doses of Covid-19 vaccines have arrived in the country.

The bulk of the shipment negotiated by the government is not expected to land till the second half of the year.