But the Helsinki firm's chief legal adviser said of the probe by the US Department of Justice Antitrust Division "the case is still pending".
General counsel Juha Mkel said: "It is an ongoing investigation and I can't disclose details. I don't know how long it will last or which firms will be involved.

"The investigators need to know if there have been illegal activities. They have strong powers. I don't think we have been unfairly targeted or that the case will be too damaging for the firm. It may clarify things and dispel doubts."

US justice chiefs granted "conditional full immunity" to past and all present employees of the firm, except former president and chief executive officer Juha Niemel (pictured), who resigned in early 2004. 

"It is not a statement that there is anything against him, but at this stage, the department isn't willing to provide him the same protection as all other staff," said Mkel.

UPM was hit with a grand jury subpoena in 2003, and this latest development follows raids over a year ago into alleged price-fixing cartels among other firms.

Competition chiefs in Finland, Germany and the US swooped on some of the industry's biggest names.

*UPM's Tervasaari paper mill 8 in Valkeakoski has been modernised to boost capacity by 45,000 tonnes a year to 175,000.