The court ruled on Thursday that the companies cooperated in raw lumber pricing for more than seven years beginning in 1997.
The ruling says that Metsäliitto and Stora Enso's forest directors met regularly and tried to influence future pricing, applying pressure on those who paid more than the average for timber.
The fines were increased because the same firms had already been fined in 2001 for restricting competition in the purchase of timber, but continued their activities.
The court said that the nation's other big forest company, UPM, had also been involved but would not be fined because it had informed authorities about the anti-competitive activities in 2004.
Metsäliitto's fine was reduced because it helped the Finnish Competition Authority investigate the case.
