Four workers at a Glanbia dairy processing plant in Co Kildare have tested positive for Covid-19.
The factory at Ballitore remains open, but the company says it has taken a range of actions on foot of the positive diagnoses.
It is understood that one member of staff tested positive on Friday and since then three more have also been found to have the coronavirus.
Wider testing is now underway among the workforce. Contact tracing has been initiated and the health and safety, as well as the quality teams are implementing planned processes.
"The health and safety of our employees, our customers and our suppliers is our top priority," Glanbia said in a statement.
"We are working closely with local health authorities and following all appropriate advice."
The company said it has had a dedicated crisis response team in place since March to ensure its 2,000 staff in Ireland are protected and that its customers continue to be served.
"We have implemented detailed site protection plans and protocols at all our locations and are managing health and safety assiduously through a comprehensive set of measures such as temperature checking at point of entry on site; heightened cleaning and sanitation; social distancing across our operations; personal protective equipment; Perspex partitions where appropriate, homeworking where possible and limiting site access to essential personnel only," Glanbia said.
The development, first reported by the Irish Farmers Journal, comes as authorities continue to take steps to deal with outbreaks among staff at a number of meat processing plants in Kildare, Laois and Offaly.
Yesterday it emerged that a mushroom plant in Co Tipperary had closed after 29 of its 170 staff tested positive for Covid-19.
The Government has announced that workers at meat and dairy processing plants are to be tested on a weekly basis for Covid-19, following the discovery of the clusters in the midlands.
In total 104 Glanbia employees work at the Ballitore plant, while an additional 30 people are employed at an independently-owned Nampak milk packaging facility on site.