Lithuanian authorities say they have detected the presence of the new coronavirus in mink at a farm in the centre of the country.
The positive tests were found in samples of 169 dead minks at the farm in Jonava district, according to Lithuania's State Food and Veterinary Service (SFVS).
One person working at the farm has also tested positive for the coronavirus, the veterinary agency said.
"The results of the study show that the SARS-CoV-2 virus could have been transmitted to tissues by a farm worker," the director of the SFVS, Darius Remeika, said in a statement.
"We urge all mink farms in the country to adhere strictly to all biosecurity requirements and to leave the workplace immediately."
According to the SFVS, the employee of the farm fell ill on Monday, and all the employees who came into contact with them are in self-isolation.
The farm was immediately closed on Tuesday, and any removal of animals, feed or other animal products from the infected holding is prohibited.
A decision was also made to cull 22 infected cages of mink and to safely dispose of the carcasses in an animal by-products processing plant.
Unlike Denmark and Ireland, Lithuania has made no plans for a mass culling of its 1.6 million population of mink at around 86 breeding farms.
Around 60,000 animals are kept at the Jonava district farm, belonging to the companies UAB Danmink and AB Vilkijos ūkis.
SFVS it was notified of the increased mortality of the mink on Tuesday and submitted samples for testing to the laboratory of the National Institute for Food and Veterinary Risk Assessment.
An additional 22 samples selected on Wednesday have also been confirmed with COVID-19.
Scientists have warned of the risk of a mutation of the virus in mink that could potentially affect the effectiveness of future vaccines against COVID-19.
But the SFVS has cited advice from the European Centre for Disease Prevention and Control which states that the virus found in mink farms does not pose a risk to human health.