Mattel and Hasbro spell out anger at online application.
The two companies which own the rights to the Scrabble board game have asked Facebook to remove the Scrabulous application from its website.
Mattel and Hasbro claim that the online version of their game is a "gross copyright and trademark infringement".
Staff at Facebook and the creators of the Scrabulous program have so far offered no comment on the request.
However, the Scrabulous website said that it only hoped to stir interest in the official Scrabble game.
"We hope this will encourage people to purchase the official board game and make sure that Scrabulous remains something that our children still come into contact with despite these days of electronic games culture," a disclaimer on the site said.
A Save Scrabulous group has already been started on Facebook and currently boasts more than 14,500 members.
An online petition has also been set up to campaign for Scrabulous, claiming that the online application has only helped spread Scrabble to new players.
"It is a popular application, with over 600,000 hits per day, and has revitalised the world's interest in Scrabble, as well as improving vocabulary and uniting people from all over the world," the petition's introduction claims.
Carolyn Abram on the official Facebook blog has previously described Scrabulous as "a great example of an application that gets better with more interactions between users, is fun and useful, and has built a loyal following that engages with it every day".