* Surge came during a few hours in afternoon, authorities say
* ICU use rate nears 80%, more beds being added
* 98.7% of recent cases show no symptoms or only mild ones
Singapore is looking into an "unusual surge" of 5,324 new infections of Covid-19, the city-state's health ministry said, its highest such figure since the beginning of the pandemic, as beds in intensive care units fill up.
Ten new deaths on Wednesday carried the toll to 349, after 3,277 infections the previous day, while the ICU utilisation rate is nearing 80%, despite a population that is 84% fully vaccinated, with 14% receiving booster doses.
"The infection numbers are unusually high today, mostly due to many Covid-positive cases detected by the testing laboratories within a few hours in the afternoon," the health ministry said in a statement.
"The Ministry of Health is looking into this unusual surge in cases within a relatively short window, and closely monitoring the trends for the next few days," it added in Wednesday's statement.
While nearly 98.7% of the past month's 90,203 cases had no symptoms, or only mild ones, about 0.2% of those had died, and 0.1% each were being monitored closely in intensive care units (ICU) or were critically ill and intubated there.
About 72 ICU beds were vacant by Wednesday, at an overall ICU use rate of 79.8%, with 142 coronavirus sufferers accounting for about half of occupied beds.
The ministry said it was adding more ICU beds. The Asian city-state, which has set aside 200 ICU beds to be used by Covid-19 patients, can add 100 more at short notice.
Last week, it extended some social curbs for about a month, to rein in the spread of Covid-19 and ease pressure on healthcare facilities.
Authorities reinstated curbs limiting social interactions and dining out to two people, so as to slow infections.