The National Bureau of Investigation (NBI) is looking into a demonstration by the far-right group Soldiers of Odin on Independence Day.
The group – which bills itself as a street patrol but has been linked to various violent incidents – had a permit for the event on Friday evening.
The NBI says it is considering whether there is reason to suspect that the demonstration was a continuation of the activities of an outlawed neo-Nazi group called the Nordic Resistance Movement (known in Finland as the PVL).
Overlap between extremist groups
Authorities note that the march featured some of the same banners and shouted slogans as PVL marches. Helsinki police said earlier that some former PVL members had taken part in the Soldiers of Odin demonstration.
The NBI already has one preliminary investigation underway into the Soldiers of Odin, which has long been linked to the PVL.
The probe is looking into suspected continuation of illegal association activities. If the investigation into the Independence Day events turns up new indications of suspected crimes, that probe will be folded into the ongoing one.
Police estimated that about 250 people took part in the Soldiers of Odin-led demonstration, while some 2,700 participated in a counter-demonstration called 'Helsinki without Nazis'. Another far-right organised demonstration, the 612 march, took its name from the date of Independence Day.
PVL temporarily banned
Last March, the Supreme Court imposed a temporary ban on PVL activities. It also granted the organisation permission to appeal a decision to shut it down completely. The ban remains in force pending a final decision by the high court.
Both the Pirkanmaa District Court and Turku Appeals Court earlier ruled that the PVL and its backing group, known as Pohjoinen perinne ('Nordic Tradition') should be disbanded.
The Appeals Court argued that it was in the general interest of society to close down the PVL due to its violent activities. In 2016, a passerby died after being attacked during a PVL demonstration in central Helsinki.
Officials rejected a planned December 6 march by a group calling itself Kohti vapautta ('Toward Freedom'), declaring that it was a front for continuation of forbidden PVL operations.