Sony is unable to restart the PlayStation Network in Japan until it provides additional security assurances to regulators, despite the service going back online in North America and Europe.
"We met with Sony on May 6 and 13, and basically we want two things from them," said Kazushige Nobutani, director of the Media and Content Industry department at the Ministry of Economy, Trade and Industry in a Dow Jones Newswires report.
"The first is preventative measures. As of May 13, Sony was incomplete in exercising measures that they said they will do on the May 1 press conference," he said, although he refused to provide exact details of the measures for security reasons.
The second regards how Sony will regain consumer confidence in Japan, given the loss of personal data - and potentially credit card data.
"There were similar cases in the past that were caused by other firms, and we are asking Sony whether their measures are good enough when compared to countermeasures taken in the past," said Nobutani.
Sony's online services went online in the UK on Sunday afternoon, as part of a phased restoration that began on Saturday in the Americas and has rolled on to Europe, the Middle East and Australasia.
Although online play, Qriocity, Sony Online Entertainment, and most other features are now active again the PlayStation Store is still not available. Sony has previously indicated that it may be until May 31 before all services are available again.
In order to use online services PlayStation 3 owners are required to download a new firmware update, which then automatically forces them to change their password.