Warner Bros. Home Entertainment Group said Tuesday it's buying a majority stake in Rocksteady Studios, the British video game developer behind the hit "Batman: Arkham Asylum."

Terms of the deal were not disclosed.

The deal expands the growing video game business of Warner Bros., a unit of Time Warner Inc. based in Burbank, Calif.

Americans spent nearly $1.2 billion on video game systems, software and accessories in January, according to a report this month from market researcher NPD Group.

Warner Bros. has made a string of video games acquisitions, including Snowblind Studios and most of the assets of Midway Games Inc.

Snowblind is expected next year to release its first game based on "The Lord of the Rings," the blockbuster movies adopted from books by J.R.R. Tolkien. Midway is behind the game "Mortal Kombat."

Warner Bros. earlier acquired TT Games, which developed LEGO Star Wars, LEGO Indiana Jones and LEGO Batman.

Rocksteady Studios Ltd., founded in 2004, is working on a sequel to the award-winning Batman game, of which three million copies were sold worldwide.