THE HAGUE, Netherlands — A Dutch man detained on suspicion of involvement in terrorism claims that he is actually an amateur sleuth who tries to track down extremists via social media, his lawyer said Friday.

Karianne Bal said that her 22-year-old client is being held on suspicion of inciting a possible terror crime, but that he was actually engaged in his “unusual hobby” of trying to unmask extremists.

“It may be an unusual hobby, but he says the (Dutch intelligence agency) AIVD and police know about it,” she said. The intelligence agency declined comment.

Bal said the man claims to pose as a radical in online chat rooms in his attempts to identify other extremists.

Prosecution spokeswoman Jeichien de Graaff also declined to comment in detail on the suspect’s explanation, saying that investigations continue into the man’s “actions, his motives and his contacts.”

An investigating judge this week extended by two weeks the custody of the man, whose identity hasn’t been released in line with Dutch privacy laws. Bal said the judge ordered her client held longer on suspicion of incitement, but said there was insufficient evidence for a more serious offense of preparing a terrorist crime.

The suspect was detained Aug. 24 following a terror threat that forced the cancellation of a concert in Rotterdam by Los Angeles rock band Allah-Las.

Dutch authorities called off the show shortly before it was scheduled to start after receiving a “concrete” tip from Spanish police about a possible terror threat.

Bal said it is unclear why the man was hauled out of his home by an armed arrest squad if law enforcement and intelligence agencies were aware of his previous efforts to track down terror suspects online.

“It looks like maybe different Dutch agencies are not communicating or cooperating,” Bal said.