It was the TV channel MTV that first reported that a network within the far right planned "serious crimes against life and health" aimed at politicians and officials in Finland.
Among other things, the network must have planned the time, method and victim in detail.
The information is confirmed by the Central Criminal Police and by prosecutors, reports MTV Uutiset.
A Helsinki police officer is suspected of involvement and is said to have been suspended from his post.
MTV Uutiset also has information that two of the cases would have been Interior Minister Maria Ohisalo and Attorney General Raija Toiviainen. But that there would be an investigation into serious violent crimes against the two people is rejected by the Prosecutor's Office late on Friday night, reports YLE.