Police in Norway say they have arrested a man after a bomb threat against Parliament put officers on high alert and shut down streets in central Oslo for several hours.

Oslo Deputy Police Chief Roger Andresen on Wednesday declined to name the suspect but said he was a Norwegian in his 20s and had made threats before. The Norwegian daily VG said the suspect had connections to the far-right, anti-Muslim Norwegian Defense League.

Police said the suspect was overheard making "unspecified" threats, including against Parliament, during a cellphone conversation on a bus Tuesday evening.

Andresen said police found a bullet-proof vest and a gas pistol in the apartment where the man was arrested. He gave no further details.