"He was arrested at Arlanda [Stockholm's international airport] on Friday by the border police. A European warrant had been issued for his arrest a long time ago by Belgium police," Swedish Security Service (Säkerhetspolisen, Säpo) spokesman Patrik Peter told AFP.
The man, a Turkish citizen whose name was not given, is reportedly 30 years old and "was remanded in custody yesterday [Saturday]. He is suspected of terror crimes," Peter said, without providing further details.
"This is a Belgian investigation," he explained.
Säpo planned to speak with the suspect on Monday to determine if he opposed extradition and Peter said he expected the process to be launched quickly, although a court would have to rule whether the man could be sent to Belgium.
According to Peter, the man's plane arrived from Syria. He added he does not know whether the man has connections to Sweden or if he has tickets for further travel.
"He has been wanted for a long time and was outside the Schengen area. He came into the Schengen area yesterday [Friday] via Arlanda. This set off an alert and the man was arrested," said Peter.
Lawyer Anders Björk would not comment on how his client responded to the allegations.
"I will not comment on that," said Björk.
A district court will decide whether to hand the man over to Belgium, generally within 30 days after the arrest.
"We will hold a hearing with him on Monday, but it is not a hearing to investigate the crimes. It is more about finding out whether he objects to being extradited," said Peter.