SAN FRANCISCO — Sony’s PlayStation network remained offline Friday on the second day of an outage that began roiling the online world just as eager video game players were unwrapping new consoles on Christmas morning.

Microsoft’s Xbox Live service, which also went down Thursday, was back online Friday although the company reported problems with some functions in the afternoon.

Credit for the disruptions was claimed on Twitter by a group of self-proclaimed hackers called Lizard Squad — or someone purporting to speak for the group. But many video game enthusiasts and some other hacker groups quickly condemned their actions. Even the notorious Kim Dotcom, a New Zealand-based online entrepreneur who’s been accused of abetting Internet piracy, got into the act by offering free vouchers for his online privacy service if the Lizard Squad would agree to restore the Xbox network.

A Lizard Squad account on Twitter appeared to credit Dotcom’s offer for the partial restoration of Xbox service on Friday.