President Rodrigo Duterte placed the entire main Philippine island of Luzon under an "enhanced community quarantine" yesterday, as measures to contain the coronavirus by sealing the capital's borders failed.

"Upon further study of worldwide trends and measures and the need for extreme caution during such a time as this, I have come to the conclusion that stricter measures are necessary," Mr Duterte said in a public address.

He said he decided to place Luzon "under quarantine" till April 13 because "I can't go into a guessing game. I have to act".

Luzon makes up a third of the Philippines, with a land area as large as South Korea and a population of over 55 million.

Metropolitan Manila, the capital region, is in Luzon.

The measures are among the strictest in place in Asia, as the Philippines grapples to contain an outbreak that has seen confirmed cases rise to 142 - from only three cases 10 days ago - with 12 deaths.

Everyone on Luzon is now on "strict home quarantine".

"Everyone will stay at home, leaving their houses only to buy food, medicine and other basic necessities for survival in the coming days," said Mr Duterte.

Most companies were told to wind down, except for banks, money transfer services, utilities, telecommunications companies, and outsourcing and export firms.

Public markets, supermarkets, groceries, convenience stores, clinics, hospitals and pharmacies will also remain open.

Most malls have decided to shut, but will keep their supermarkets and pharmacies open. Restaurants will be limited to providing take-out and delivery services.

Buses, jeepneys, trains and all mass public transport have been grounded.

But movement of cargo will be unimpeded.

"We cannot really control the contagion. We want it to be perfect. But there will be downsides," said Mr Duterte, as he sought to allay unease over these measures.

He urged companies to consider an early disbursement of the 13th-month pay of their employees to help them tide over the situation, and landlords to suspend rent and leases.

The government would also extend financial help to the most affected small and medium-sized businesses, he added.

The government stepped up its efforts to contain the virus after the lockdown imposed on Metro Manila buckled yesterday morning, its borders overrun by massive numbers of people and vehicles coming through.

At many key junctions, traffic ground to a near standstill. Commuters, pedestrians and motorists swarmed roads leading to Metro Manila, as they squeezed their way through dozens of checkpoints set up to enforce the lockdown.

Metro Manila has a population of nearly 13 million. In the day, that number swells by three million as those living in the suburbs head to the capital for work.

The government had allowed them to cross into Metro Manila.

Spanning 16 cities, it entered into a sweeping, month-long lockdown on Sunday to prevent the spread of the coronavirus to other parts of the Philippines.

Individual cities have also passed ordinances imposing an 8pm to 5am curfew.