One of Britain's biggest food companies, 2 Sisters Food Group, said it suspended production on Thursday at a poultry processing plant in North Wales for 14 days after a COVID-19 outbreak.
2 Sisters Food Group, which produces around a third of all poultry products consumed in the UK, said it would transfer production to the company's other plants until July 2.
It said a first member of staff at the plant at Llangefni on the Isle of Anglesey tested positive for COVID-19 on 28 May.
Public Health Wales said in a statement that there had now been 58 confirmed cases at the plant and all employees and contractors had been asked to self-isolate for 14 days.
The plant employs 560 people.
There have been a series of COVID-19 outbreaks at meat processing plants across Europe and the Americas.
An outbreak at an abattoir in northern Germany prompted one of Germany's largest meat processors, Toennies, to stop slaughtering on Wednesday.