The article included extracts from "Les Fossoyeurs" (The Gravediggers), a 388-page book by journalist Victor Castanet that alleges poor treatment of the group's elderly residents at a site outside Paris.

"We formally reject all of these accusations, which we consider to be false, outrageous and prejudicial," the company said in a statement.

It added that has already contacted its lawyers to take all necessary steps, including legal action.

Orpea is one of Europe's biggest for-profit care home operators alongside French rival Korian, with a network of 1,156 facilites and more than 90,000 beds across 23 countries spanning Europe, Asia and Latin America.

The group is rapidly expanding, adding over 1,000 new beds over its third quarter last year, as it looks to increase its revenue by more than 14% to over 4.2 billion euros ($4.74 billion) this year compared to before the pandemic.

The Paris stock exchange had suspended trading at Orpea's request at 1145 GMT, pending the release of the statement, as the stock headed down 16% towards its worst-ever single-day performance, while shares of Korian dropped over 10%.

Published by Paris-based Fayard, "Les Fossoyeurs" is set go on sale on Wednesday, Jan. 26.

($1 = 0.8855 euros)

(Reporting by Sarah Morland, Juliette Portala and Valentine Baldassari; editing by Jason Neely and David Evans)