Danish police detained several people on Thursday on suspicion of preparing terrorist attacks.
The arrests were made in coordinated operations across the country, police said.
Authorities haven't specified the number of arrests, however a press briefing scheduled for 13.00CET is expected to give more details.
Prime minister Mette Frederiksen deemed the facts "extremely serious", speaking from Brussels, where she's attending a key EU summit centred around Ukraine's accession hopes.
Terror threat levels rising across EU
Denmark's current terror threat alert is at level four, the second highest.
Thursday's arrests come only two days after the Netherlands announced raising their terrorism threat level to "substantial".
EU Home Affairs commissioner Ylva Johansson recently warned that Europe faces a "huge risk of terrorist attacks" over the Christmas holiday period, linking it to the Israel-Hamas war fallout.
Anti-Islam activists stirring tensions in Denmark
In an effort to prevent radicalisation, earlier this year Denmark passed a bill banning Quran burning.
The law makes it illegal to desecrate any holy text, after a handful of anti-Islam activists carried out public desecrations of the Quran, sparking outrage in majority-Muslim countries.
Denmark is not new to terrorism episodes.
In July 2022, a gunman at a shopping mall in Copenhagen killed three people and injured seven. The man, who believed the victims were zombies, was sentenced in July to detention in a secure medical facility.
He had been charged with murder and attempted murder in the rampage at the huge Field's shopping center, on the outskirts of Copenhagen.
In 2015, a 22-year-old Danish Muslim gunman killed two people and wounded five others at a free speech event and a synagogue in Copenhagen.
The Quran is full of surahs asking the faithful to commit terror attacks on Danish Christmas fairs this year ...