Hasbro and Mattel, the marketers of Scrabble, are accusing the creators of popular Facebook app Scrabulous of violating the copyright on the 70-year-old word game and are demanding that the social network remove the app from its site, the BBC reported. So far, both Facebook and Scrabulous not commenting. But neither have ceased operating the game, which does at least closely resemble Scrabble. Late Wednesday afternoon, both the Scrabulous site and the Facebook app were accepting new players. The Scrabulous site does explain that it has no affiliation with Scrabble, while encouraging users to buy the Scrabble board game. That’s not enough to mollify Hasbro and Mattel.

Scrabulous, which claims to attract more than 500,000 daily players, was created last year by two brothers in Calcutta. But it didn’t take off until it was added to Facebook a few months ago, where it quickly became one of the top 10 apps. It’s attracted a devoted following: a cursory glance at Facebook shows about a half dozen “Save Scrabulous” groups; the largest one has over 9,000 members.

—FT: Scrabble’s ownership is divided between Hasbro, which holds the copyright in the US and Canada, while JW Spear & Sons, a UK-based unit of Mattel, has the intellectual property rights in rest of the world. Aside from Scrabulous’ popularity, a red flag was likely raised when Hasbro and Mattel became aware of Scrabulous’ claim that it earns $25,000 a month in ad revenue. And it seems that Scrabulous’ fans have helped bolster the claims that it was harming Scrabble; as one user who identified herself as “Cat” on Scrabulous’ blog wrote: “I was going to purchase the dvd scrabble but now i decided not. This is much more fun playing.”