The prosecutor has asked Uppsala District Court to have the man remanded in custody pending an ongoing investigation. A preliminary court hearing is expected to take place on Thursday.
According to court documents seen by The Local, the man is suspected of preparing to commit a terrorist offence. The allegations apply to the period September 1st-November 13th in Stockholm or Uppsala.
The prosecutor has asked the court to remand him on either 'probable cause' (the higher degree of suspicion according to Swedish law) or 'good grounds' (the lower degree). The different degrees of suspicion dictate how long a suspect can be locked up before charges are pressed.
"I am very surprised based on the information I have received, but it is possible that the police and prosecutor have information that I do not have," the man's lawyer, Leif Silbersky, told TT.
Prosecutor Ewamari Häggkvist told Swedish radio P4 Uppland that the allegations were based, among other things, on a search of the man's house in Håbo municipality, north-west of Stockholm.
"The preliminary investigation measures consist of customary interrogations, searches and seizures," she said, but declined to comment on the details of the alleged offence, including suspected motives.
The man, who is a Swedish national, was arrested on Sunday and questioned on Tuesday. According to his lawyer he then denied the accusations.
On his Facebook page, the suspect has linked to right-wing extremist content. However, both the prosecutor and his lawyer declined to comment on whether or not the alleged offence was linked to racism.
The Dagens Nyheter newspaper spoke to unnamed sources close to the 33-year-old, who described him as critical of immigration but neither politically active nor a member of any far-right organizations.
Earlier this year a former teaching student was locked up for five years for plotting a suicide attack in Sweden. It was the first verdict of its kind in Sweden.