Los Angeles-based mobile game maker Jamdat Mobile Inc. is being acquired by video game giant Electronic Arts Inc. for $680 million, or $27 per share a 21 percent premium over Wednesday’s closing price of $22.34 per share.

The companies announced the agreement Thursday afternoon in a press release, stating that directors of both companies already had approved the deal. Jamdat has 350 employees worldwide.

The companies did not say if employees would be relocated to EA’s Redwood City headquarters, only that the mobile businesses would be combined into one unit, EA mobile games worldwide, to be run by Jamdat chief executive Mitch Lasky.

The acquisition is expected to close in EA’s fourth quarter, ending March 31. While some video game publishers launched their own wireless divisions Calabasas-based THQ Inc. has THQ Wireless, for example EA primarily licensed its console game titles to other companies for adaptation to cell phones.

With a market cap of $565 million, Jamdat is the biggest mobile games publisher. It has spent the past year and a half acquiring smaller game developers, and now holds the popular Tetris, Bejeweled and Jamdat Bowling titles. Through licensing agreements, it also adapts console games for cell phones.

Jamdat has licensed titles like Electronic Arts’ “Madden NFL Football” and “FIFA Soccer,” as well as Santa Monica-based competitor Activision Inc.’s “Tony Hawk” franchise for mobile phones.

The Jamdat acquisition could put a wrinkle Activision’s mobile game plans. In November, Jamdat signed a co-publishing agreement with Activision for exclusive worldwide mobile gaming rights for the next “Tony Hawk” game and the new “Gun” franchise.