A 16-year-old Danish Muslim girl arrested in January was planning to carry out bomb attacks against two schools, one of which was Jewish, Danish police said on Tuesday.
The girl was allegedly helped by a 24-year-old man who Danish media said had been fighting in Syria, though it was not clear for which group, according to the preliminary charges presented in a court in the town of Holbaek, 70 kilometers (45 miles) west of Copenhagen.
The girl, a recent convert to Islam, is accused of obtaining chemicals and preparing bombs to attack two schools: a Jewish school in Copenhagen and another one where she was once a student, according to broadcaster TV 2.
The girl was arrested on January 13 while the man turned himself in to police the following day.
Both deny the charges, which were only revealed to the public on Tuesday.
Police said they were unable to comment further as the case was being investigated "behind double-locked doors", meaning information is withheld from the media and the public.
The Danish Security and Intelligence Service said in a statement there was "no reason to change the assessment of the terror threat against Denmark, which remains serious."
On Thursday, four Danish men are to go on trial accused of aiding a Copenhagen gunman who killed a filmmaker and a Jewish security guard in twin attacks in February 2015.
AFP contributed to this report.