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Sony's breached PlayStation Network may well be offline longer than the company had expected, according to a Sony executive.

In a post on Sony's PlayStation.Blog late yesterday, Patrick Seybold, senior director of corporate communications and social media for the company, said Sony was still performing security checks on the system and that it might not be back up and running in the originally announced timeframe. Part of the problem, Seybold said, has been the hitherto unknown size of a breach of the Sony Online Entertainment gaming network, discovered during Sony's investigation into the PlayStation intrusion.

"When we held the press conference in Japan last week, based on what we knew, we expected to have the services online within a week," Seybold wrote. "We were unaware of the extent of the attack on Sony Online Entertainment servers, and we are taking this opportunity to conduct further testing of the incredibly complex system."

Meanwhile, the company said today that on Thursday it removed 2,500 customer names and partial addresses that had been 'stolen by hackers and posted on a Sony Web site. The names belonged to mostly U.S. customers who had entered a contest in 2001. 'Sony said the Web site was "out of date and inactive" when discovered and that the company took the page down. CNET reported on Thursday that hackers were planning to break into an unspecified Sony Web site this weekend and post information gleaned from the attack somewhere online.

PlayStation chief Kaz Hirai said last Saturday that most services on the PlayStation Network would be restored "within the week," including online game play for the PlayStation 3 and PlayStation Portable' chat functionalities' and the ability to play downloaded movies from PSN and to play unexpired movie rentals through PSN and Qriocity. Hirai said the company hoped to restore the entire network, including the PlayStation Store and purchasing features, "within the month."

The network went down in late April and it took Sony about a week to notify customers that the system had been breached by an unknown entity, who gained access to millions of customers' personal data--including, perhaps, credit card information. The company has since been criticized--by members of Congress, among others--for keeping customers in the dark and for what some see as lax security measures.

On Thursday, CEO Howard Stringer apologized for the outage and breach and attempted to explain Sony's delayed response. The company also announced details regarding third-party identity-theft monitoring services it will offer free to U.S. customers affected by the breach.

In yesterday's post, Seybold didn't say when the system would be back online.

"We've begun the process of restoring the service through internal testing of the new system," he wrote. "We're still working to confirm the security of the network infrastructure, as well as working with a variety of outside entities to confirm with them the security of the system. Verifying the system security is vital for the process of restoration. Additional comprehensive system checks and testing are still required, and we must complete that process before bringing the systems online."

CNET's Erica Ogg contributed to this report.

Updated at 6:17 p.m. PDT with details about the posting and removal of some customer information.