Sony Corp believes it was targeted by hackers because it tried to protect its intellectual property, CEO Howard Stringer told a shareholders' meeting on Tuesday.

No one has claimed responsibility for the massive April hacking attack in which details on 77 million user accounts were leaked, but many have speculated that the attack was sparked by Sony's efforts to clamp down on unauthorized use of its PlayStation games console.

(Reporting by Isabel Reynolds; Editing by Edmund Klamann)