Uzbek citizen Rakhmat Akilov has admitted to committing the truck attack in Stockholm on April 7, SVT reported.
"His position is that he admits to a terrorist crime and accepts therefore that he will be detained," the lawyer representing him said in a court hearing to decide whether he should be kept in custody.
Police believe Akilov, 39, was the driver of the hijacked beer truck that mowed down pedestrians on a street in the Swedish capital before crashing into a department store.
He was arrested on the highest level of suspicion in the Swedish legal system. Akilov was already wanted by police for failing to comply with a deportation order.
Security services said he had expressed sympathies with extremist organisations, but had not viewed him as a militant threat, Reuters reported.
Four people were killed and 15 more were injured when a lorry was driven into a department store on Friday.
