An association representing 400 French book publishers has joined La Martinière Groupe in its lawsuit to stop Google from digitising books for its Google Book Search service.

La Martinière filed a suit against Google and its French subsidiary in a French court on 6 June, accusing the search engine of counterfeiting. It asked the court to stop the search engine from scanning its books, and demanded €1m (£668,000) in damages. The publisher said Google had illegally copied at least 100 of its copyright works and included them in its Google Book Search without permission.

Google Book Search allows readers to find citations in the books that Google has scanned.

"The French Publishers' Association is intervening alongside La Martinière Groupe... to defend the interests of the profession," the association said.

The association said that Google had digitised, in addition to works in the public domain, a number of protected works, and had allowed access to multiple extracts from these works through its search engine Google Book Search without the permission of the rights holders, with no regard for the fundamental rules of the law of IP (intellectual property).

One of the issues at stake is the way Google presents the search results: they are shown graphically as a ragged-edged piece of paper, as if torn from a book.

That angers the French publishers because it portrays their work as just one step away from the rubbish bin, said Tessa Destais, a spokeswoman for La Martinière.

"We know that Google is powerful, but it has to show some respect for books," she said.

Destais expects the court to begin its action before the end of the year.