All the mills have already been awarded Programme for the Endorsement of Forest Certification (PEFC) chain of custody certification.

The paper manufacturer said it wanted to offer customers the chance to use the chain of custody certificate of their choice.

UPM's Caledonian Paper mill in Scotland has had both FSC and PEFC chain of custody certificates since 2004. UPM has 22 paper and pulp mills in eight countries.

Some 19 of these use virgin fibre in their production, four of which have both FSC and PEFC certification, and 11 hold PEFC certificates.