Microsoft Corp's Xbox Live was back up on Friday while Sony Corp's PlayStation Network remained offline for a second day after a hacker group claimed responsibility for attacking the two Internet gaming services.

Gamers on Xbox Live and PlayStation Network experienced connection problems and delays on Christmas Day, one of the busiest times of the year for the video game industry. The majority of game and console sales are generated during the end-year holiday shopping season.

A message on PlayStation Network's website on Friday read: "Under Scheduled Maintenance. We should be back online shortly. Apologies for any inconvenience." It directed users to the PlayStation blog and other related websites.

A Microsoft website that keeps track of the status of Xbox services listed Xbox Live's "core services" as up and running on Friday. Several third-party apps on the platform were experiencing limited services, however.

A hacking group called "Lizard Squad" took credit for the disruption to both Xbox Live and PlayStation Network on Thursday.

The group appeared unrelated to the "Guardians of Peace" hackers who broke into Sony Pictures' network earlier this month to try to stop the release of the film "The Interview," which depicts the assassination of North Korean leader Kim Jong Un.

"The Interview" was released online on Wednesday on the Xbox network and other digital platforms. The movie also hit select US theatres on Thursday.

Lizard Squad could not be reached for comment. Xbox and PlayStation representatives were not immediately available for comment.