More than 1,300 people were wrongly told they had coronavirus due to a lab error with NHS Test and Trace.
The Department of Health and Social Care (DHSC) said 1,311 people who took a test between November 19 and 23 across the UK were incorrectly told they received a positive result.
It said there was an issue with a batch of testing chemicals which meant their results were void.
A DHSC spokesperson said: “Swift action is being taken to notify those affected and they are being asked to take another test, and to continue to self-isolate if they have symptoms.
“This laboratory error was an isolated incident and is being fully investigated to ensure this does not happen again.”
The DHSC did not comment on whether the error affected regional figures of infection rates.