The five men from Kankaanpaa in the southwest were aged “around 25” and were arrested on Tuesday morning after being under surveillance for two years, police told a news conference.
Material found in the men’s possession “reinforces the impression that they have become radicalised and gives reason to suspect them of terrorist offences”, Detective Superintendent Toni Sjoblom said in a statement.
“A significant quantity of guns, ammunition and explosives” were recovered during a home search in December 2019 when the men were arrested on firearms charges, Sjoblom said.
According to police the men appear to be motivated by “accelerationism”, a white supremacist ideology that has been linked to mass shootings in the US, in which followers aim to sow division and inter-racial tensions in society.
Police declined to reveal the planned target of the attack but said the arrests marked Finland’s first case of suspected far-right terrorism. There was no danger to the public, police said.
Residents of Kankaanpaa who know some of the suspects told Finnish newspaper Helsingin Sanomat that one was a “skinhead” and that two others were “known as neo-Nazis”.
Police said that the EU’s law enforcement agency Europol was also involved in the investigation, but that the group did not appear to belong to an extremist organisation.
“A small group like this which idealises terrorist violence works in secret and their activity does not involve contact with organised publicly operating extreme-right groups,” Pietila said.
Photos released by the police showed one of the suspects in a balaclava posing with a handgun and a machete, while a second photo showed weapons confiscated from the group including a semi-automatic rifle, homemade explosive devices and bundles of dynamite.
In an update in March, Finland’s security services Supo said they would keep the terrorist threat level at “elevated”, the second-lowest level on a four-point scale.
However, they warned that the risk from far-right extremism was “more worrying” than in the previous year. “This case has been a key driver of that threat assessment,” Supo specialist researcher Eero Pietila said.