Sony's PlayStation Network has been suffering from connection issues for the fourth straight day after hackers brought down the popular gaming network on Christmas Day. The company, however, can only say that it is gradually restoring the service.

The hack attack was carried out by the Lizard Squad, who claimed to be behind the disruptions of both the PlayStation Network and its rival Xbox Live by Microsoft on Dec. 25.

Service for Xbox Live, however, was fully restored on the following day of Dec. 26.

"We are currently experiencing widespread network issues that are being addressed," wrote Sony on the maintenance website of the network.

The operations of the PlayStation Network have been intermittent, with fluctuations on the availability of the service. Sony Computer Entertainment America VP of consumer experience Catherine Jensen wrote on a post in the PlayStation blog that the PlayStation Network has been restored, only to see the network go down again a few hours after.

"From time to time there may be disruptions in service due to surges in traffic, but our engineers will be working to restore service as quickly as possible," Jensen also wrote.

While there are some players that said on Twitter that they have been able to gain access to the PlayStation Network on Sunday, there were more complaints on the ongoing outage.

A specific figure on the number of the affected gamers out of the 56 million PlayStation users has not been specified.

The customer support account of Sony on Twitter, Ask PlayStation, tweeted that the services of the PlayStation Network is "gradually coming back online," but did not specify a target date and time for gamers to expect the network to be fully restored.

"PlayStation Network and some other gaming services were attacked over the holidays with artificially high levels of traffic designed to disrupt connectivity and online gameplay. This may have prevented your access to the network and its services over the last few days," Jensen wrote on the PlayStation blog regarding the attacks, describing the DDoS attacks that the Lizard Squad is known for.

The Lizard Squad revealed that it was behind the DDoS attacks that brought down the PlayStation Network in August and early December. The hack attack back in August came with a bomb scare, as the Lizard Squad sent a tweet to American Airlines claiming that there were explosives aboard an airplane wherein a Sony Online Entertainment executive was on.