Eighteen factory workers at a Bernard Matthews turkey processing site in Suffolk have tested positive for the coronavirus.
Public health officials have had to test one hundred members of staff who work at the plant, located in Holton, near Halesworth.
Bernard Matthews said those who tested positive for Covid-19 - from the Great Yarmouth and Lowestoft areas - were now self-isolating.
The turkey processor employs around 1,000 people at the Suffolk site.
Food production has not been affected by the outbreak, Bernard Matthews and public health officials said in a joint statement.
A spokesman for the company said: "We believe these small number of cases were initiated in the community, but nevertheless we will continue to enforce our robust Covid measures as we enter into our busiest period of the year."
The firm said it was continuing with regular temperature checks, staff working in bubbles, Covid-19 marshals, masks and visors, and social distancing throughout the site.
Stuart Keeble, Suffolk's director of public health, said: "I'd like to reassure people that this is, at this stage, a relatively small number of cases and that the situation is being very carefully managed by all the partners working closely together."
Bernard Matthews is not the first meat processor to have had coronavirus cases amongst its workforce.
In June, Asda was forced to temporarily shut down its West Yorkshire meat site after 165 staff tested positive for Covid-19.
2 Sisters - which produces a third of all poultry products consumed in the UK - shut its Anglesey meat plant after an outbreak infected 13 factory workers.
Elsewhere, in Germany, Europe's largest meat processing site was hit by an outbreak which resulted in approximately 7,000 people being quarantined.