Sony’s PlayStation network remains down for a third day although

the company said on Saturday morning in a tweet that its PS4, PS3, and Vita network services were gradually coming back online.

The service disruptions hit eager online gamers as they unwrapped their new consoles on Christmas morning.

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

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 other hacker groups quickly condemned their actions.

Even the notorious Kim Dotcom, a New Zealand-based online entrepreneur who has 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 the Xbox service. But exactly what happened is still unclear.

Neither Sony nor Microsoft would say what disrupted their networks and experts say it is difficult to trace the source of attacks or confirm claims of responsibility.

Sony Online Entertainment said on its website that its Playstation network was still down, adding on Twitter: “We are working to restore full network services for all platforms - thanks, as always, for your patience!”

A Microsoft support site said Xbox Live was available yesterday evening UK time, but reported new problems later.

Signs of trouble emerged earlier this month when someone using a Lizard Squad account on Twitter began threatening to disrupt gaming services at Christmas and then boasted of causing the outages on Thursday.

A person or group using the same name on Twitter took credit last August for similar attacks in which hackers overwhelmed company servers with a flood of internet traffic, disrupting the online gaming networks operated by Sony, Riot Games and other companies.

The same Twitter account was also used in August to make an apparently false report that a bomb was on an aircraft carrying a Sony executive.

So far there is no specific evidence to link the episodes with last month’s malware attacks on Sony’s film division. The current episode does not appear to have exposed any corporate or customer data, but one expert said the Lizard Squad group was capable of serious disruption.

"They're well-practised and, from what I see, they've got the capability to take down a lot of things," said Dan Holden, director of security research for Arbor Networks, a cyber-defence company based in Burlington, Massachusetts. He said little was known about the group or where its members were based.

“Their cause is a little bit oddball,” said Mr Holden, adding that the group appears to be motivated primarily by a desire for visibility and “lulz” — internet slang for laughs. Mr Holden said he recently described them on his blog as “hacktivists” or online political activists, until the group contacted him on Twitter and asked to be called “cyber-terrorists”.

He said the attacks caused economic damage to gaming companies. “It’s certainly costing money all the way around to defend against these attacks,” he said, adding that Sony may also face the wrath of customers whose brand-new PlayStations would not work on Christmas Day.

Lizard Squad's claimed attack on Sony's gaming network last summer has also prompted speculation it might be involved in the November hack of Sony Pictures Entertainment, which the FBI has blamed on North Korea.

While experts say it is possible the North Korean government worked with independent hackers, Mr Holden also noted that Lizard Squad Twitter accounts appeared to applaud the internet outage that afflicted North Korea this week.

“It’s totally speculative,” he said of suggestions that Lizard Squad might be involved in the Sony Pictures attack.

Meanwhile, someone using a Lizard Squad Twitter account claimed the group was shifting its attention to attack a widely used internet encryption service called Tor.

Later a Tor spokeswoman said the service was responding to an attack but did not expect any “performance effects”.

PA