SINGAPORE - Advisories will be issued to all laboratories conducting coronavirus tests to ensure that test results are accurate, said the Health Ministry's director of medical services, Associate Professor Kenneth Mak, on Tuesday (May 12).

The advisories describe standard processes that the laboratories have to follow to make sure they are producing accurate tests that are performed correctly.

This follows the ministry's announcement on Sunday that 33 false positives had been detected as a result of an "apparatus calibration issue".

The laboratory involved subsequently stopped testing, and is in the process of recalibrating its test kits and revalidating test results. The number of Covid-19 tests that could be carried out each day decreased as a result.

The recalibrating should take place over the next few days, following which Singapore will be able to return to its full testing capacity, Prof Mak said.

"To safeguard this particular process of quality assurance and to make sure we avoid having false positive results coming out in the future, we have put together some advisories and guidances for all the labs involved in testing," he added.

Even with measures in place to make sure testing is done properly, there may be a need for confirmatory tests to be done in some cases, Prof Mak said.

In such cases, laboratories will be required to perform confirmatory tests before Covid-19 test results are released.

"(This is) so that we have greater confidence in the test results being accurate," he said.