Sony said it would begin restoring its PlayStation videogame network in Japan and elsewhere in Asia Saturday, more than a month after a massive security breach leaked personal details on tens of millions of accounts.

The Japanese electronics and entertainment giant, which has already begun restoring services in other parts of the world, said on Friday it would also offer a new identity protection service to customers in Asia.

In what is thought to be the biggest security breach of its kind, hackers accessed personal information on 77 million PlayStation Network and Qriocity accounts, 90 percent of which are in North America and Europe, and may have stolen credit card information.

Gamers and security experts had criticized Sony for its handling of the incident, which sparked lawsuits and cast a shadow over its plans to combine the strengths of its content and hardware products via online services.

The company apologized to customers for the outage, and said a range of new security measures had been introduced. These included an early warning system that could alert the company to any attempt to penetrate the network.

Japan's trade ministry on Friday ordered the firm's gaming unit, Sony Computer Entertainment, to adopt measures to improve the management and security of personal information, following the data breach.

Considering the content and volume of information leaked, it is an extremely grave incident, and it is truly regrettable that it occurred and took a considerable time to notify users and the ministry, the ministry said in a statement.

COUNTING COSTS

On Thursday, Sony said it was keeping to its target of restoring all PlayStation Network services by the end of May, with any delay beyond that not likely to be more than a few days.

It has said it expects the hacking to drag down operating profit by 14 billion yen ($172 million) in the current financial year, including costs for boosting security measures.

Some users had said the prolonged outage had prompted them to switch to rival Microsoft's Xbox Live games service.

Sony discovered unusual activity on its PlayStation Network, which enables games console owners to download games, chat with friends and pit their skills against rivals, on April 19.

It shut down the network and its Qriocity online music and movie service, frustrating many users, but waited almost a week before alerting users to the extent of the security leak.

The company later found out that a separate online games service had also been penetrated, allowing access to another 25 million user accounts.

(Reporting by Isabel Reynolds; Writing by Anshuman Daga; Editing by Lincoln Feast)