Rajat Agarwalla, left, and his brother, Jayant, play Scrabulous.

NYT / J. ADAM HUGGINS

Toymaker Hasbro Inc. filed suit in federal court yesterday against the two brothers who created Scrabulous — a wildly popular online version of Scrabble — saying the electronic game infringes on the Pawtucket company’s intellectual-property rights.

Hasbro also notified the social-networking site Facebook of the lawsuit. The toymaker requested that Facebook block the Scrabulous game application from the network’s users in the United States and Canada as soon as possible.

“Hasbro has an obligation to act appropriately against infringement of our intellectual properties,” said Barry Nagler, the company’s general counsel. “We view the Scrabulous application as clear and blatant infringement of our Scrabble intellectual property, and we are pursuing this legal action in accordance with the interests of our shareholders and the integrity of the Scrabble brand.”

Hasbro owns the rights to distribute Scrabble in the United States and Canada, while Mattel Inc. owns the rights to distribute it elsewhere.

The lawsuit comes about a year after two brothers in Calcutta, India, launched their own version of the game as an application on the popular Facebook site. The introduction of Scrabulous, created by Rajat and Jayant Agarwalla, prompted legal threats from Hasbro and Mattel.

Hasbro has now followed through on its threat, naming the brothers and RJ Software as the defendants in the lawsuit filed yesterday in the U.S. District Court for the Southern District of New York. Mattel did not join the action.

The filing follows the launch earlier this month of Hasbro’s own version of Scrabble for social-networking sites. Mattel launched its online version of Scrabble in March.

Hasbro’s online Scrabble game is among the first the toymaker has licensed for such use. The company developed its newest version of Scrabble in conjunction with California-based Electronic Arts Inc. The game was launched this month on Facebook and Pogo.com.

Scrabble is the first Hasbro title in a set of free online games expected to be introduced this year on Pogo. EA Scrabble games are available on mobile phones and Apple Inc.’s iPod in the United States and Canada.

In the Hasbro-Electronic Arts version of the game on Facebook, players can choose a real-time turn-based game. They can pause a game and resume it later. Players can choose the speed and level of play, and track scores, statistics and rankings, as well as chat online with other players.

In an interview earlier this month, Mark Blecher, general manager of Hasbro digital media and gaming, said the company is moving to meet demand for interactive online games.

“We understand the current popularity and potential of Web-based social-network game play for a wide range of our toy and game brands,” he said.

In a statement released yesterday, Blecher said: “Hasbro and EA have worked diligently to provide a great game play experience on Facebook, and we are confident that fans of the game will welcome a genuine experience highlighted by top-of-the-line graphics, strong technical support, and of course, classic Scrabble game play.”

Scrabulous, the virtual knockoff created in 2005 by the Agarwalla brothers, has proven enormously popular, with more than 700,000 players a day and nearly 3 million registered users.

The Scrabulous version has a board that looks just like Scrabble’s and has the same number of letter tiles with the same point values. Players can search for opponents through Facebook. Scrabulous also tracks player statistics.

Hasbro and Mattel threatened to force Facebook to take down the Scrabulous application because they view it as a copyright violation.

“Scrabulous very much infringes our intellectual property [rights],” Blecher said in the earlier interview.

Scrabble’s 15-by-15 grid and basic rules are familiar to board game fans around the world.

In the traditional game, players each randomly select 7 lettered tiles from a pool of 100, each indicating a point score of 1 to 10, depending on the letter. Players then take turns arranging their tiles into words on the grid, and they add up the point values. Values increase when tiles are placed on various bonus squares.

Last August, Hasbro signed a license with Electronic Arts to make video, cell phone and other digital games for the Scrabble, Yahtzee and Tonka brands.

pgrimald@projo.com