Workers at a food processing plant are to be tested for coronavirus after four people associated with the factory tested positive for Covid-19.
Public Health Wales (PHW) said it was investigating the cause of the confirmed cases associated with Zorba Delicacies.
It said "widespread, rapid testing of the workforce" would begin on Tuesday "as a precautionary measure".
The company in Ebbw Vale, Blaenau Gwent, employs about 490 people.
PHW communicable disease control consultant Dr Rhianwen Stiff said: "Close contacts of confirmed cases have been contacted through the test, trace, protect process and provided with additional advice for themselves, household and other contacts."
She added: "As we move into the recovery phase of the coronavirus pandemic, we expect to see clusters in settings such as workplaces."
Dr Stiff said it has not been declared as an outbreak.
Last month there were 634 confirmed Covid-19 cases at food factories in Llangefni, Wrexham and Merthyr Tydfil.