Sony failed to get its Playstation Network (PSN) up and running again this weekend as it had hoped to.
The Japanese electronics firm said it still had to ensure users' data was safe, with further testing required to guarantee the system's robustness.
Sony promised it would improve security following attacks on PSN and the Sony Online Entertainment (SOE) division, which together saw data on over 100 million users stolen.
"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," Sony said in a blog post.
"As you've heard us say, our utmost priorities are the security of the network and ensuring your data is safe. We won't restore the services until we can test the system's strength in these respects."
Sony is working with external companies to ensure the quality of the network's security, making "additional comprehensive system checks."
"We must complete that process before bringing the systems online," the firm added.
On Friday, Sony chief executive (CEO) Sir Howard Stringer apologised to users for the hacks.
Stringer said the company had not disclosed the breaches sooner as it wanted to have adequate understanding of the compromises and not risk relaying false information.
Another hack?
Over the weekend, Sony had to deal with another hack, albeit a significantly less serious one.
Names and partial addresses of 2,500 sweepstakes contestants from a 2001 competition were stolen by hackers and posted online, Reuters reported.
Sony successfully took the website down, with no credit card or social security information having been exposed.
