The number of coronavirus cases linked to the 2Sisters factory in Coupar Angus has almost doubled.
Health chiefs confirmed on Monday afternoon that 57 people have so far tested positive, with more than 80 employees in quarantine.
An Incident Management Team was set up to monitor the outbreak at the George Street abattoir five days ago, when the number of cases stood at 30.
Dr Emma Fletcher, who chairs the IMT, has insisted that the factory does not need to close.
It is the second outbreak at the George Street plant since August when around 200 out of more than 1,000 staff tested positive. At that time, the factory was ordered to close for two weeks.
New cases emerged at the factory just after Christmas.
Dr Fletcher said that the new total of 57 cases represented “an expected increase”.
She said: “The Incident Management Team remains reassured that the factory can remain open at this time as we are in a very different position to when there were COVID-19 cases at the factory last August.”
Health chiefs believe that measures put in place after the last outbreak are helping to reduce the risk of transmission within the building.
“These have been reviewed regularly and assurance provided by the relevant regulatory authorities,” said Dr Fletcher. “Secondly, the incidence of the infection in the community is much higher compared to August.
“Therefore, we will identify cases of COVID-19 in employees of 2 Sisters, as in any workplace, at this time. Many of the cases are likely to have contracted the infection outwith the factory setting.”
She added: “We can confirm that contact tracing of the positive cases to date is ongoing and over 80 employees who were working in the areas of the factory which have been identified as having been directly affected, are self-isolating as a precaution.
“The factory is continuing to work closely with NHS Tayside’s Public Health team and Food Standards Scotland to help manage the situation.”
Dr Fletcher said the case was being kept under close review and the IMT will meet again on Friday.
Health chiefs had suggested that the outbreak was being brought under control just before New Year.
But it emerged that a sharp rise in cases may have been linked to an indoor party involving a small minority of staff on Hogmanay.
The gathering was branded “idiotic” by local MSP and Deputy First Minister John Swinney.
A spokesperson for 2Sisters said: “Last year, all colleagues were given extensive guidance on conduct in the community and how to keep Covid safe in a shared household.
“Any colleague suspected of breaching guidelines will be subject to disciplinary action.”