July 30 (Reuters) - International Paper ( IP ) and other

rival manufacturers have been accused in a new lawsuit in U.S.

federal court of conspiring to fix and inflate prices for key

raw materials that are used to make cardboard boxes and

merchandise displays.

The proposed class action filed on Tuesday in the federal

court in Chicago said International Paper ( IP ), Packaging Corporation

of America ( PKG ), Georgia-Pacific and several other companies

collectively raised prices by 30% since late 2020.

Mt. Vernon, New York-based Artuso Pastry Foods Corp filed

the lawsuit on behalf of what it said was at least hundreds of

thousands of buyers. The lawsuit said containerboard raw

materials are used in pizza boxes, moving boxes, banker boxes

and more.

The lawsuit said the manufacturers violated U.S. antitrust

law through "numerous unprecedented and unjustified price

increases, often implemented at the exact same time and for the

exact same increase."

International Paper ( IP ) declined to comment. Georgia-Pacific and

Packaging Corporation of America ( PKG ) did not immediately respond to

requests for comment, and neither did defendants Smurfit

Westrock ( SW ) and Greif ( GEF ).

Graphic Packaging ( GPK ), also a defendant, in a statement

said it was "confident in our practices and committed to

operating with integrity."

Attorneys for the plaintiffs did not immediately respond to

a request for comment.

The lawsuit said the defendants inflated prices for

containerboard and linerboard, the materials that make up

finished products such as cardboard boxes. The companies also

make and sell boxes and other containerboard products, according

to the lawsuit.

Price increases in the corrugated box market "drastically

outpaced" what the lawsuit described as a modest rise in demand

over the period covered by the complaint.

As demand fell in recent years, the lawsuit said, price

increases continued.

The lawsuit said that in a competitive market, companies

that raise prices substantially would not expect rivals to do

the same thing.

The plaintiffs are seeking more than $5 million in alleged

damages and a court order prohibiting any continued violations

of antitrust law.

The case is Artuso Pastry Foods Corp v. Packaging

Corporation of America ( PKG ) et al, U.S. District Court for the

Northern District of Illinois, No. 1:25-cv-08856.

For plaintiffs: Vincent Briganti of Lowey Dannenberg;

Christopher Burke of Burke LLP; Eric Unrein of Cavanaugh, Biggs

& Lemon; and Gary McCallister of McCallister Law Group.

For defendants: No appearances yet

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