Danish police on Thursday arrested four men on suspicion of volunteering to fight for the Islamic State in Syria.
The arrests were made in the greater Copenhagen area in cooperation with the Danish police security service PET, a statement said.
Police declined to offer further details or give information about the intelligence they had acted on.
A remand custody hearing was due on Friday. The prosecution said it will request a closed door session.
Justice Minister Soren Pind welcomed the arrests saying they were an indication that the authorities were on the right track in efforts to stop volunteers wanting to join terrorist groups in Syria and northern Iraq.
According to a PET assessment from March, at least 115 people have travelled from Denmark to Syria or Iraq to join jihadist groups such as the Islamic State. At least 19 of them have died.