More than 140 people have tested positive for coronavirus at a meat processing factory in Norfolk.
Norfolk County Council said the positive test rate at Cranswick Country Foods in Watton, which produces pork products, was a "cause for concern".
The authority said 144 out of 333 staff tested have given a positive result and now all 1,000 staff at the plant would be tested.
The BBC has contacted the factory for comment.
A council spokesman said the decision over whether to close the factory is not one for the local public health team but they "are liaising with the Joint Biosecurity Council and keeping them updated on the situation".
Cranswick also has poultry processing sites at Kenninghall, Norfolk, and Yaxley, Suffolk.
It is one of several meat processing plants which have experienced an outbreak of coronavirus among staff.
Turkey producer Bernard Matthews in Holton, Suffolk, has been affected since last month, and a small number of workers at its site in Great Witchingham, Norfolk, tested positive.
Banham Poultry closed for two weeks in August and September when more than 120 staff had the virus.