Sony has disappointed users by being unable to confirm the restart date of its PlayStation Network.
The company, under fire since hackers accessed personal data from about 100 million users, had previously said the PlayStation gaming network would be able to resume normal operations within a week.
"We were unaware of the extent of the attack on Sony Online Entertainment servers, and we are taking this opportunity to conduct further testing," Sony said in a blog.
"We won't restore the services until we can test the system's strength in these respects."
Sony also admitted that it had found names and partial addresses of 2,500 sweepstakes contestants posted by hackers on a website, but that it had removed these postings from the internet.
The data came from Sony customers who entered a 2001 product sweepstakes contest but did not include information on credit cards, social security numbers or passwords.
"The website was out of date and inactive when discovered as part of the continued attacks on Sony," Sony said.
Sony CEO Howard Stringer has apologised to users of the firm's PlayStation Network and other online services for the massive data breach.
PlayStation services were initally supposed to be restored within a week but the latest update from Sony was that this would not be possible, and that no date had been fixed for the restart.
The incident may prove to be a significant setback for Sony, which has been outmanoeuvred by Apple in portable music and Samsung in flat-screen TVs.
In video games, it faces a tough fight with Nintendo's Wii game console and Microsoft's Xbox.
"This wait is becoming so tedious. I know there needs to be a lot of testing, but it is really getting annoying. I am seriously considering changing to the Xbox," said a user called Cryonic UCX posting on the U.S. PlayStation blog.
Sony shares last week ended 2.3 per cent lower in a broader market down 1.5 percent, extending its total losses to about six per cent since it revealed the breach.
Sony only warned users of the PlayStation break-in a week after it detected a problem with the network, saying it had needed time to work out the extent of the damage.
The hackers have not been identified, but Internet vigilante group Anonymous, which had claimed responsibility for previous attacks on Sony and other corporations, denied it was behind the data theft.
The group's statement came after Sony said Anonymous was indirectly responsible for the attack on the company.
Sony, which is set to report its annual earnings at the end of the month, has yet to specify the financial effect of the network breach.