Packager Amcor has rejected the valuation by an expert retained by claimants in a class action against it over alleged price-fixing of the extent of damages at issue in the case.

The expert economist has estimated damages of $466 million might be due, as well as an estimated $231 million in interest, Amcor said in a statement on Friday.

Amcor said it "strongly disputes" the estimate of damages and would refute it with its own experts in the course of arguing the case before the court.

Amcor is defending a case brought by claimants represented by Jarra Creek Central Packaging Shed Pty Ltd, alleging price-fixing and market rigging.

It is estimated about 17,000 companies in Australia were major customers of cardboard boxes, each buying more than $100,000 worth of the goods between May 2000 and May 2005.

Lawyers Maurice Blackburn say they have a list of hundreds of those customers that allege they were victims of cartel behaviour.

In its statement on Friday, Amcor said the economist's report had been released to the parties to the action.

"The report estimates, based on a range of disputed and contentious facts and assumptions, that the damages suffered by Amcor customers... are potentially in the vicinity of $466 million plus an estimated $231 million in interest," Amcor said.

"Amcor strongly disputes the estimate put forward and will dispute the facts and assumptions upon which the report appears to be based.

"Amcor is continuing to vigorously defend the claim and will, in the course of the litigation, put forward independent expert evidence refuting the incorrect assumptions and conclusions in the plaintiff's economist report."

Amcor said it was too early to provide any reliable assessment of possible damages if its defence was unsuccessful in whole, or in part.

It also was too early to say what contribution could be expected from the other defendent in the case, rival packager Visy Industries.

© 2010 AAP