Trade Union Pro has said its members at forest products giant UPM will walk off the job on New Year's Day if the company does not agree to a new collective agreement.

The strike will last three weeks, as will a threatened strike by the Paper Workers' Union at UPM facilities in Finland.

The current collective agreement covering Pro workers runs out on 31 December, and union representatives say UPM has declined all invitations to negotiate a new deal.

UPM wants the flexibility to vary conditions of work for staff doing the same job in different units within the company, but the unions are resisting that change.

UPM is therefore planning to unilaterally introduce new terms of work from the start of the year, without agreement with the unions.

Traditionally Finnish labour talks have been sector-wide, with a collective agreement guaranteeing industrial peace between unions and companies.

This time, employers' organisations have declined to negotiate a sector-wide deal, preferring to negotiate company-by-company.