The initial strike was due to last for two weeks but was extended as talks continued with the unions calling for a further extension to at least the beginning of March.

The agreement will increase salaries by 3.3% over a 25 month period, and increase annual production time of factories by 24 hours through shortening midsummer stoppages in late June, Finnish Forest Industries association said in a statement.

"The changes are a step in the right direction, but are inadequate for ensuring the international competitiveness of Finnish factories," the association said.

Stora Enso, one of Finland's biggest paper producers, has said the strike cost it €11m for each week of industrial action.