Danish environmental authorities are looking into whether decomposing mink buried in dirt pits after a nationwide cull could contaminate groundwater and nearby protected nature areas.
The Danish government ordered a cull of about 17 million mink in early November after hundreds of farms suffered outbreaks of coronavirus and authorities found mutated strains among people.
Authorities buried some of the mink under two metres of soil in a military area in western Denmark.
They now want to dig them up after some resurfaced from the graves, most likely due to gases from the decomposition process.
The mink cull has become a Danish scandal, with Prime Minister Mette Frederiksen in tears when she apologised over the government's botched handling of the crisis.
It was ordered when it was thought the mink outbreak could jeopardise the effectiveness of future vaccines.
But a few days after the cull began, the government was forced to admit it did not have enough legal basis to order the kill.
Now, a new study, first reported by Reuters, said groundwater near the burial pits could quickly become contaminated. It urged the authorities to take swift action.
"It is the groundwater just below the graves that is in imminent danger of becoming contaminated," said Per Schriver, at the Environmental Protection Agency.
The graves were not above reservoirs of drinking water and were far away from local waterworks, but the contaminated groundwater could migrate to nearby streams or lakes, causing pollution, Mr Schriver said.
The study was commissioned by the agency in late November and was prepared by the Geological Survey of Denmark and Greenland, and the Technical University of Denmark.
The agency is conducting more tests assessing the environmental effects of the graves. It said on Wednesday that it expected the results of those early next year.
Before interring the dead mink, authorities said the burials would not pose a risk to drinking water or protected areas.
The burial sites are guarded 24 hours a day to keep people and animals away, and have drawn complaints from residents about possible health risks.
