Sony's PlayStation network was back online yesterday following a cyberattack that took it down over the weekend.
A hacker group claimed responsibility for the attack, and also tweeted about a possible bomb on board a flight carrying a Sony executive in the United States.
Sony said on its PlayStation blog that the gamers' network had been taken down by a denial- of-service attack, which overwhelmed the system with traffic but did not intrude onto the network or access any of its 53 million users' information.
The hackers behind the attack said they had also targeted the servers of World of Warcraft video game maker Blizzard Entertainment, whose website was down, and threatened to attack Microsoft's Xbox Live game network, which was also experiencing problems.
A Twitter user with the handle @LizardSquad  claimed responsibility for the PlayStation attack on Sunday, and said the attack was meant to pressure the company to spend more of its profits on the network.
"Sony, yet another large company, but they aren't spending the waves of cash they obtain on their customers' [PlayStation Network] service. End the greed," one post said on Sunday.
Sony's network business has been hit by attacks before, with a security breach in 2011 dealing a major blow to plans at the time for a looser network designed to allow for the connection of a range of Sony devices.
Since then it has invested heavily in the system and is now hoping the network can serve as a centrepiece of its plans to rebuild its business after years of losses on its electronics operations.
Xbox spokesman David Dennis said: "We don't comment on the root cause of a specific issue, but as you can see on Xbox.com/status  the core Xbox Live services are up and running."
Blizzard Entertainment could not be reached for comment, though its customer support Twitter account said the company's servers were stabilising.
Lizard Squad also tweeted to American Airlines on Sunday to say it had heard that explosives were on board a flight carrying Sony Online Entertainment president John Smedley.
That followed an earlier tweet from a game player's forum telling the airline: "I'm gonna send a bomb on your plane be ready for me tomorrow."
A PlayStation spokeswoman in the US said the Federal Bureau of Investigation was probing the diversion of the flight from Dallas/Fort Worth to the west coast city of San Diego.
The FBI had no comment on the incident.
American Airlines said on its Twitter account that it was "aware of threats" made over the microblogging service and had alerted security.