LONDON, June 28 (Reuters) - Activision Blizzard (ATVI.O) said its studio that developed "Call of Duty" would set up shop in Barcelona, putting into action its pledge to invest in Europe after Brussels approved Microsoft's $69 billion acquisition of the company in May. In contrast, it said it would "meaningfully expand" its investment and workforce in the European Union after the deal received the green light there. Microsoft and Activision Blizzard are battling antitrust regulators on both sides of the Atlantic to clinch the deal, the biggest ever in video gaming. Activision Blizzard CEO Bobby Kotick and his Microsoft counterpart Satya Nadella are due to testify in a court in San Francisco on Wednesday to urge a judge to allow the merger. Microsoft is appealing the British veto with the "aggressive" support of Activision.

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Persons: Bobby Kotick, Satya Nadella, Kate Holton, Alexander Smith Organizations: Activision, Digital Legends, Microsoft, European Union, Activision Blizzard, Atlantic, Federal Trade Commission, Thomson Locations: Barcelona, Europe, Brussels, U.S, Spanish, Guildford, Warrington, England, European, San Francisco, Britain