MP Juho Eerola's assistant, Ulla Pyysalo, says she applied for membership in the Finnish Resistance Movement without being aware of all of its views. The group espouses a national socialist, anti-immigrant agenda.
The daily Helsingin Sanomat reports that the Finns Party board will discuss the revelation at a meeting on November 19. It quotes the chair of party's parliamentary delegation, Pirkko Ruohonen-Lerner, as saying the issue is very serious and could lead to expulsion from the party.
In July, Pyysalo made headlines when she posted an offensive joke on her Facebook page about Greens MP Jani Toivola.
Eerola and Toivola are both first-term MPs, while Ruohonen-Lerner has been in Parliament since 2007.