A one day strike started on 22 October while the four day strike started on 29 October and ended today. Both involved managers and supervisors at mills across the country.

The strikes are over the Finish Forest Industries Federation's "intractable position" over awarding overtime pay and compensation on business travel when done outside business hours, according to ICEM.

Dick Blin, pulp and paper officer at the Federation, said he understands the mills have continued to operate throughout the strike.

He said the Federation of Professional and Managerial Staff (YTN) "has been futilely negotiating with the industry grouping since September 2009".

It is understood that new talks have not yet been scheduled.

Päivi Kauhanen, director of communications in Finland at Stora Enso, confirmed that the company is involved in the four day strike but said "it has not had any effect on production in any mills".

She said: "All our Finnish mills are involved but only around 10% of the people belonging to the specific group of white-collars are participating."

The company also had a one-day strike one and a half weeks ago as well, and only less than 10% of the people belonging to the specific group of colleagues participated.

A spokesman for UPM said he could not confirm at this time whether UPM staff were involved in the strike.

However, he said: "The white collar strike has not affected UPM production."