Sony Corp. missed a deadline to restart operations of its online-gaming services, citing the need to test security improvements to its computer networks in the wake of a massive data breach.

The company on May 1 said it aimed to get gaming, music and video services of the PlayStation Network and Qriocity services up within a week. But a Sony spokesman late Friday acknowledged that it wouldn't resume operating over the weekend, the deadline indicated by its earlier statement. He declined to specify a new time frame to restore...