Caledonian vice president and general manager Gordon Mitchell said the investment was an extension to the mill's current mechanical pulp facilities.

He said it would allow the firm to strengthen the quality of its bleaching processes at the plant. "In these tough times it's a good endorsement for the mill to get an investment such as this," said Mitchell.

Mitchell stressed that the plant was not looking to use the investment to develop new products or increase production.

The Irvine-based paper mill was certified to both the Programme for the Endorsement of Forest Certification (PEFC) and Forest Stewardship Council (FSC) chain of custody standards in March this year.

UPM Caledonian Paper produces coated magazine papers, namely its UPM Cote and UPM Ultra brands, and has a production capacity of 270,000 tonnes per year.