A Norwegian court on Friday remanded a Syrian-born 16-year-old on suspicion of planning a terrorist attack, a day after his arrest in Oslo.
The teenager - whose name was sealed - was to be held in pre-trial custody for two weeks, the Oslo district court ruled.
The court said remand was necessary considering the gravity of the allegations and lack of a juvenile facility with sufficient security.
The Norwegian police security service PST had requested remand, citing fears that the suspect otherwise could harm the investigation.
The court also ruled that his mail and visits be strictly vetted.
The suspect denied the allegations, and his lawyer demanded his release.
After the closed-door hearing, police attorney Thomas Blom told reporters that the PST had acted on "troubling" information received on Wednesday. "We believe he has made preparations for an act of terrorism... in Norway," Blom said.
Blom added that the investigation was at an early stage, but police have seized various items and recorded online activity that would be analyzed, though he did not offer details.
The court statement said that the suspect had been in possession of "dangerous substances" that he appeared intent on using.
According to Blom, the suspect has not answered police questions.
Oslo tabloid VG earlier cited PST sources as saying the 16-year-old supported the Islamic State terrorist group. He was reunited with his family in Norway some years ago.
The PST last year said that the main terrorism threat facing Norway was Islamist-motivated, or extreme right-wing, conducted by a lone assailant.