The Ministry of Health (MOH) yesterday announced two deaths - that of a 68-year-old Singaporean man from complications due to Covid-19, and of a 53-year-old Indian man who died of a heart attack.

This brings the country's death toll from the virus - those whose primary or underlying cause of death is Covid-19 - to 21 cases.

Another seven, including the Indian man, have so far died from other causes although they tested positive for the coronavirus.

Offering an explanation for making this distinction, MOH said: "Only cases where the attending doctor or pathologist attributes the primary or underlying cause of death as due to Covid-19 infection will be added to the Covid-19 death count. This is consistent with international practice for classifying deaths."

It noted that 86 male migrant workers aged 25 to 59 died due to heart disease in Singapore in 2018.

The explanation comes as questions have been raised recently about how deaths are classified.

The Indian national died last Saturday from a ruptured myocardial infarction due to coronary thrombosis, the ministry said. He had been sent to the Sengkang General Hospital emergency department after suffering a cardiac arrest that day.

He was confirmed to have Covid-19 on Sunday, after his death.

The Singaporean who died from Covid-19 had a history of hypertension and hyperlipidaemia, and the National University Hospital has reached out to his family to assist them, MOH added. He was confirmed to have Covid-19 on April 5.

Yesterday, Singapore reported one of its lowest daily increases in recent weeks, partly due to fewer tests being processed after an equipment fault produced false positives over the weekend. While the number of cases has fallen below 1,000 in the past week, it has generally ranged between 600 and 800, unlike the 486 cases reported yesterday.

The day's cases take the country's total count to 23,787, the highest in South-east Asia.

Meanwhile, three new clusters were announced - Tuas South Apartments, 47 Senoko Drive and 566 Woodlands Road.

The new cases comprised one Singaporean, one permanent resident, one work pass holder, two work permit holders staying outside dormitories and 481 migrant workers staying in dorms.

MOH said it is still conducting extensive testing in dormitories, including factory-converted dorms. S11 Dormitory @ Punggol, Singapore's biggest cluster, which on Sunday reported no new cases, saw four more cases yesterday and now has 2,543 confirmed cases.

With three weeks left till Singapore's circuit breaker measures are expected to ease on June 1, MOH data shows positive signs that cases outside dorms could be under control.

The ministry said the number of local cases, excluding dorm residents and other work permit holders, has continued to fall, from nine cases daily two weeks ago to eight in the past week. Its tracing efforts have found that fewer of these are unlinked - from a daily average of five to three over the same period.

Yesterday, 504 patients were reported to have been discharged, higher than the number of new cases. To date, 3,218 patients in Singapore have fully recovered and been discharged, while 24 are in critical condition in the intensive care unit.