Union spokesman Jukka Riksman said the strike by 20,000 employees demonstrated the depth of concern at the spate of recent redundancies.

The goal was to show employers that their politics are wrong, Riksman said. We knew that it was not going to change their decisions, but we wanted to show them what we thought.

Both UPM and Stora Enso said the strike would not affect deliveries to customers in the UK and elsewhere.

Stora Enso vice-president for investor relations and financial communications Ulla Paajanen-Sainio said there was no agreement reached because the union had not made any demands.

We gather it is not happy but we understood that earlier redundancies are never nice, she said. We are committed to proceeding with our profit improvement programme.

The strike, which closed mills from 6am Monday to 6am Wednesday last week, affected all paper manufacturers in Finland, including UPM and Stora Enso, and is estimated to have cost the sector well over 14m (21m) in lost profitability.

UPM plans to close its Voikkaa paper mill in autumn and cut 2,500 jobs in Finland over the course of the next three years. Stora Enso has announced a round of cost savings, including 2,000 job cuts and the closure of 10 mills worldwide.