A food processing plant in Perth and Kinross has been closed after nine people connected to the factory tested positive for Covid-19.
NHS Tayside said one other individual connected to the 2 Sisters plant in Coupar Angus was awaiting results.
Arrangements are currently being made to test all employees.
Close contacts are being advised to self-isolate and all other identified contacts are being followed up and given advice.
Earlier, the health board said there were two cases in the community.
2 Sisters said the temporary closure was "the responsible action to take."
NHS Tayside Public Health was first alerted to the outbreak on Sunday.
Management at the poultry factory, which employs about 1,000 people, made the decision on Sunday night to temporarily close the factory.
It is understood a manager at the factory may have caught the virus from a close relative, who is not an employee of the plant.
The company said in a statement: "Our priority remains the safety and wellbeing of all colleagues, and we will be reviewing the situation closely in partnership with the relevant regional and national Scottish Covid-19 taskforces before we restart production.
"The facility had previously operated for six months without a single positive Covid-19 case recorded."
An incident management team is working with Scottish government, Public Health Scotland and local environmental health teams to provide advice and support.
Deputy First Minister John Swinney said, "Where clusters of cases develop we must find them and act quickly to prevent further spread.
"Public health teams in Tayside are responding quickly to this outbreak and we are liaising closely with them, Food Standards Scotland and Perth and Kinross Council to discuss all appropriate measures to contain this cluster.
"However, individuals who have been in this plant should be extra vigilant, ensure they follow all public health advice, and if they have any symptoms of Covid-19 should isolate and book a test on the NHS website."
Food Standards Scotland chief executive Geoff Ogle said, "There is currently no evidence that food is a source of coronavirus (Covid-19), and it is very unlikely Covid-19 can be transmitted through the consumption of food or food packaging.
"However as with other infections, good hygiene practices should be followed throughout every element of food preparation."