Danish police have arrested a 30-year-old man who planned to carry out an attack in Copenhagen using knives and explosives.

The Ekstra Bladet tabloid says the man, who was not named, was a 30-year-old Syrian national known to Swedish intelligence as dangerous for his sympathies with the Islamic State group.

Police on Friday confirmed the Thursday arrest but declined to elaborate, citing an ongoing pre-trial custody hearing.

The tabloid said the arrested man likely was an accomplice of a Syrian refugee who in July was sentenced to 6.5 years in prison in Germany for planning a terror attack in Denmark.