The companies that make the board game Scrabble are trying to shut down Scrabulous, an online version that is one of the most popular applications on the social networking site Facebook.
Hasbro Inc., which owns the rights to the crossword game in the United States and Canada, and Mattel Inc., which owns the rights elsewhere, believe the online game, developed in India, infringes on their copyrights and trademarks.
Scrabulous listed more than 600,000 daily active users on Facebook as of Wednesday and is one of the 10 most used applications on the site. People can also play at Scrabulous.com.
Hasbro and Mattel jointly issued cease-and-desist notices to four parties involved in the development, hosting and marketing of Scrabulous, according to a letter Hasbro is sending consumers who have contacted them about Scrabulous.
In a separate written statement released Wednesday, Hasbro did not name the four parties but said it was reviewing a number of options with them and hoped to find an amicable solution.
"If we cannot come to one quickly, we will be forced to close down the site and its associated distribution points," Hasbro said.
Scrabulous' co-developer, Jayant Agarwalla, said in an e-mail that he usually does not comment on legal issues. Facebook did not return several requests for comment.
While there are authorized Scrabble games online, Scrabulous has gained popularity because it is free, easy to play with friends and easy to access on Facebook.
The game was developed by brothers Rajat and Jayant Agarwalla, from Calcutta, India, who say on the Web site that they created it after they could not find an online version of Scrabble that they liked.
News of the toy companies' action prompted Scrabulous fans to start a "Save Scrabulous" group on Facebook and urge others to lodge protests with the companies by posting Web links to the Hasbro and Mattel sites.
In the letter Hasbro is sending to those who protest, the company urges Scrabulous fans to switch to legal Scrabble sites.
"We are not surprised that fans have thoroughly enjoyed playing Scrabulous on Facebook.com," the letter says. "What consumers may not realize, however, is that Scrabulous is an illegally copied online version of the world's most popular word game."
John D. Williams Jr., executive director of the National Scrabble Association, said the group was hopeful the companies could work out some sort of agreement. While most competitive Scrabble players do not play Scrabulous, he said the online game was a great way to introduce young people to the traditional board game.
"We're thrilled over anything that gets people playing more Scrabble," he said. "Our goal is to recruit them from the Internet and get them playing on a Scrabble board with a person sitting across from them."