All 1,000 Bernard Matthews staff at its Great Witchingham site are being swabbed for coronavirus after several confirmed cases.
Norfolk County Council confirmed on Friday morning that testing was underway after some staff tested positive.
They would not say how many were positive, but a council spokesman said they believed that those who had contracted the virus had not become infected at the site.
They said the mass testing was being carried out as a precaution to find if there were any asymptomatic staff.
It comes after all staff at the meat producers factory near Halesworth in Suffolk were swabbed this week, after 72 workers tested positive.
Dr Louise Smith, Norfolk’s director of public health, said: “This testing is a sensible, precautionary measure that will help us understand who at the site has COVID-19 and who else they may have been in contact with.
“We would remind everyone across Norfolk, to continue to act responsibly, respect the Rule of Six and follow the government’s guidance.”
A spokesman for Bernard Matthews said: “We can confirm a small number of positive cases at our site at Great Witchingham.
“These colleagues and their contacts are now self-isolating at home, and we will continue to work closely with public health officials to monitor the situation. There is no evidence these transmissions occurred in the factory. Food production and safety remain unaffected.”
There have been outbreaks at meat factories across the country, including Banham Poultry near Attleborough, leading to companies putting in stricter measures.
•Anyone with Covid-19 symptoms should self-isolate immediately and apply for a test.
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