UPDATE 1-Activision countersues former executives

* Says ex-Infinity Ward execs threatened game franchise

* Says former execs negotiated with competitors (Adds comment from lawyer)

SAN FRANCISCO, April 9 (Reuters) - Activision Blizzard Inc ATVI.O has countersued two former executives, charging them with attempting to "hijack" the company's assets and threatening the future of its blockbuster "Call of Duty" video game franchise.

Activision fired Jason West and Vincent Zampella last month. The men, who lead the Infinity Ward studio, subsequently filed a lawsuit against Activision, seeking $36 million in royalty payments and damages.

Infinity Ward, which was acquired by Activision in 2003, developed the original “Call of Duty” game and several others in the series.

In a cross-complaint filed on Thursday in California Superior Court in Los Angeles, Activision said it fired both men for cause after they violated their employment contracts and their fiduciary duties to the company.

The complaint charged that West and Zampella were “insubordinate and self-serving schemers” who negotiated with competitors while under contract, and tried to prevent Activision from compensating Infinity Ward employees in order to make them “easier to poach” when the men departed to set up their own company.

It also charged that West and Zampella held future “Call of Duty” versions “hostage” because of their demands.

Robert Schwartz of O’Melveny & Myers, a lawyer for West and Zampella, called Activision’s allegations “false and outrageous” in an emailed statement.

“This is just an Activision tactic to avoid paying Jason and Vince and everyone else at Infinity Ward the millions of dollars they all earned and that Activision owes them,” he said.

“Call of Duty: Modern Warfare 2,” the sixth installment in the series, was released late last year and sold nearly 12 million units in the United States, Japan and the United Kingdom in 2009. It set a record for first-day sales, moving 4.7 million copies and pulling in an estimated $310 million.

After firing West and Zampella, Activision formed a business unit for the “Call of Duty” franchise. A new title is scheduled for release this fall.

The case is Jason West v Activision Publishing, Superior Court of the State of California, No. 107041 (Reporting by Gabriel Madway; Editing by Phil Berlowitz, Gary Hill)