The health products regulator is investigating reports of antigen test brand Genrui producing false positive results.
The tests are available in a wide variety of Irish supermarkets.
The Government brought antigen testing to the front line defence against the virus by making it policy for those aged between four and 39 to test positive on an antigen test before getting a PCR test to confirm it.
The new rules came in on January 3 and there has since been widespread reports of shortages of the rapid tests.
The move appeared to contradict comments made by Deputy Chief Medical Officer Ronan Glynn when he called antigen tests "snake oil".
In a statement, the Health Products Regulatory Authority (HPRA) said it had received a "number of reports" about the potential issue.
They said: "The HPRA is following up with the manufacturer of the test to investigate the matter and will also liaise with other European Competent Authorities in relation to this issue.
"We would encourage individuals who have experienced a false positive or negative result to report the occurrence to the HPRA at devicesafety@HPRA.ie."
Cork GP Dr Niamh Ni Loinsigh posted on social media that hundreds of people had contacted her about false positive test results with the Genrui brand.
She wrote on Twitter: "Received 100s of messages through my Insta about Genrui antigen tests. When pcr was available there seemed to have been lots of false positives with these kits. This could have major implications for people now with no pcr available."
Share your views on reopening schools below, or click here.
To get the latest breaking news straight to your inbox, sign up for our free newsletter.
