The number of Covid-19 cases in Japan topped 10,000 yesterday as the country hunkered down for its first weekend under a nationwide state of emergency, haunted by the spectre of a breakdown of the healthcare system.

People stayed home in many areas, heeding the call by Prime Minister Shinzo Abe, who said on Friday that a blanket emergency decree was necessary to invoke a sense of urgency to prevent the spread of Covid-19 across porous city borders.

At a nationally televised news conference, he apologised to medical front-line workers for Japan's inability to secure enough medical equipment such as N95 masks, ventilators and personal protective equipment, which has led to fears of an institutional collapse.

Pledges of mask donations to Japan have come from overseas, including from Taiwan and Vietnam.

Japanese companies have also joined the Covid-19 fight. Carmaker Nissan is making face shields, cosmetics maker Shiseido is producing hand sanitiser, while electronics giant Sony is making ventilators.

Textile maker Teijin is now making medical gowns, while beverage maker Suntory is offering hospitals free alcohol disinfectants.

This comes as the Health Ministry has asked doctors to sterilise and reuse their N95 masks amid the shortage, while the city of Osaka is collecting unused plastic raincoats to re-purpose into medical gowns.

Japan's "cluster-based" testing approach has helped to keep a lid on group infections at one location quickly, but it has not been able to curb the spread of the disease throughout the country.

It has since relaxed testing requirements and expanded screening in a policy U-turn that is a tacit acknowledgement that its approach has been toothless against an invisible threat, given the surge in cases with no known routes of transmission.

This is one reason behind the recent surge in numbers across the country, including 181 cases in Tokyo yesterday. There were 10,213 cases as of 7pm yesterday, about twice the number nine days ago.

Elsewhere in Asia, Indonesia yesterday extended stricter social distancing rules to millions living on the main island of Java and in West Sumatra as it reported 325 new cases, taking the total in the vast country to 6,248.

Malaysia recorded just 54 new cases yesterday, the lowest number since March 18, taking its total to 5,305.

South Korea confirmed just 18 new Covid-19 cases yesterday, bringing its total to 10,653. Cases in the country have tapered off, largely because it tested widely from the outbreak's onset.

Japan's recent spike means it will overtake its neighbour in a matter of days.

Despite signs of more aggressive polymerase chain reaction testing, Japan is still screening at only about half its national capacity of 12,000 tests daily.

Latest figures from the Health Ministry show that as of noon yesterday, the country of 125.9 million has done tests for 111,325 people, with 4,953 of them newly tested over the preceding 24-hour period.

This is less than half the testing capacity, even though Mr Abe had said earlier this month that Japan would boost its screening capacity to 20,000 tests a day.

There are several reasons behind this reluctance to test more widely.

Until recently, sclerotic bureaucracy mandated that all infectious disease patients be given a hospital bed, though the lack of beds has forced a belated revision of the law to allow recovery at home or hotels.

Tests are also not readily available for everybody and are done only if a doctor deems them necessary, thus making it difficult to detect cases that manifest in mild symptoms.

And there is the crippling manpower shortage at hospitals.

The Japanese Association for Acute Medicine and the Japanese Society for Emergency Medicine said in a joint statement last week: "The first sign of the collapse of medical care is the collapse of the emergency medical system, which has already happened."

They noted that some hospitals were so overstretched that they have had to reject patients seeking treatment for other urgent illnesses like strokes and heart attacks.

But the unfurling crisis has led local medical associations to step up to the plate. General practitioners in Suginami ward in Tokyo have volunteered to take test samples to reduce the burden on their colleagues at large hospitals.

Chiba prefecture has rolled out drive-through testing after the green light was given by the Health Ministry last Wednesday. More prefectures may follow suit.

"With help from regional medical associations, we will set up testing centres. If home doctors have decided testing is necessary, test samples are taken at these centres and sent to private inspection firms," Mr Abe said.

"This will lessen the burden on public health centres."