In efforts to forestall the spread of a mutated variant of the coronavirus, the government ordered about 17 million mink culled, devastating an industry recognised in the fashion industry around the world for its high-quality furs.
While Danes broadly approved of Frederiksen's initial handling of the pandemic, the Social Democratic minority government was thrown into turmoil when it emerged that there had been no legal basis to order the cull of healthy mink.
The incident eventually led to the exit of the agriculture minister and parliament commissioned an inquiry into whether ministers including Frederiksen had known that the legal framework was absent when the order was made.
Other high-ranking officials were also included in the inquiry.
The prime minister's office's actions "led to the gross misleading of mink breeders and the public and the clearly illegal instructions to authorities," the commission behind the probe said in its report to parliament.
It was not immediately clear whether a majority in parliament would favour an independent legal assessment of the probe's results, which could prompt a launch of an impeachment case.
Opposition parties have earlier expressed support for an impeachment.
The prime minister will respond to the criticism at a news conference on Friday morning.
Frederiksen, who sat before the commission in December, blamed the oversight on the government's heavy workload.
She has apologised publicly but has maintained that the decision was sound and based on the assessments by health authorities.
She said in an interview this week that she expected strong criticism from the commission but did not see grounds for an impeachment.
