Sony Corp's No.2 Kazuo Hirai will brief media on Sunday about a huge security breach of its PlayStation Network, the first time an executive of the electronics giant will publicly address the case, which could prompt global legal actions.

Hirai, in line to succeed CEO Howard Stringer, will hold a news conference in Tokyo at 2:00 pm (0500 GMT) on Sony's investigation of the case, its information management system and the schedule to resume services, the firm said in a news release on Saturday.

Sony warned on Tuesday that hackers had stolen names, addresses, and possibly credit card details from 77 million user accounts of its online video game network, which produces an estimated $500 million in annual revenues.

The disclosure of one of the biggest ever online data infiltrations came on Tuesday, a week after Sony shut down the network. Executives made no mention of the crisis hours earlier that day when they launched its first tablet computer.

The delay prompted anger among online users, although company said it was due to a forensic investigation.

It could lead to legal action around the globe and pose a challenge for Hirai, who Stringer has said is in pole position to succeed him.

In the US, attorneys general, who act as consumer advocates, have begun investigating the matter or reviewing it with staff in several states, while U.S. regulators such as the Federal Trade Commission could get involved as well.

The chairman of the U.S. House of Representatives' Committee on Energy and Commerce, Mary Bono Mack, on Friday sent a letter to Hirai, who also serves as the chairman of Sony Computer Entertainment America, asking why the disclosure was delayed.

In Britain, a government watchdog launched an investigation of the incident.

Sony has been mulling a potential successor for Stringer, who has been vague about his plans from the next financial year that starts in April 2012.

Hirai, who was promoted in March to executive deputy president of Sony, used to run the firm's network products and services division including Sony's game businesses.

Sony shares took a hit on Thursday, falling nearly 5 per cent in Tokyo. The bourse was closed on Friday, a national holiday.

Sony said it had encrypted all credit card numbers, which would make it extremely difficult for hackers to access that data. But criminals might use other personal information that was not encrypted to launch scams. – Reuters