SINGAPORE, May 11 (CNA) - Singapore reported 486 new COVID-19 cases as of noon on Monday (May 11), taking the national total to 23,822.

The vast majority of the cases are work permit holders residing in foreign worker dormitories, said the Ministry of Health (MOH) in its daily preliminary update.

Two cases are Singaporeans or permanent residents.

"The lower number of cases today is partly due to fewer tests being processed at a testing laboratory as it is recalibrating its apparatus for one of the test kits," said MOH.

More details and updates will be shared later in the day, the ministry added.

33 "FALSE POSITIVES" IDENTIFIED

On Sunday, MOH said 33 previously confirmed COVID-19 cases from a laboratory were found to be "false positives", including a healthcare worker who worked at the Singapore Expo community care facility.

"MOH regularly reviews the laboratory tests and recently found that 33 cases from a laboratory were false positives, due to an apparatus calibration issue for one of its test kits," the health ministry said.

Subsequent retesting of the cases at the National Public Health Laboratory confirmed that these were negative cases, MOH said.

The ministry said it took immediate action to rectify the situation.

A total of 425 patients were also discharged on Sunday, the highest number of discharged cases seen in a day in Singapore since the COVID-19 pandemic.