The story has been changed on the wire and the first, second, third, sixth and ninth paragraphs now read:

Twitter Inc. has launched a comprehensive review of the defenses in its popular social network and microblogging service after hackers hijacked the accounts of several high-profile users on Monday.

In interviews this week, analysts said they were surprised that sites like Twitter , potentially hot targets for hackers and phishers, had long avoided such major attacks, and thus strong scrutiny by its corporate users.

Since the widely-publicized hack of the site, analysts said they are closely watching how Twitter and especially its corporate customers respond to the security breach.

San Francisco-based Twitter confirmed on Monday that hackers had broken into the accounts of more than 30 celebrities and organizations, including President-elect Barack Obama, Britney Spears, and the Fox News and CNN cable television networks.