Sony has responded to a House committee query about the breaches of PlayStation Network and Sony Online Entertainment as lawmakers ripped the company's efforts to inform consumers.

The hearing conducted by the House of Representatives' Committee on Energy and Commerce focused on the threat of data theft to American consumers.

In a letter submitted to Congress, Sony Computer Entertainment chief Kaz Hirai says the company "has been the victim of a very carefully planned, very professional, highly sophisticated criminal cyberattack designed to steal personal and credit card information for illegal purposes."

Sony turned down a request to attend the subcommittee hearing to continue its investigation into a data breach that knocked out the PlayStation Network on April 19 and Sony Online Entertainment earlier this week.

Their absence did not stop lawmakers, including Rep. Mary Bono Mack, R-Calif., from blasting the company for its slow response to consumers.

"In Sony's case, company officials first revealed information about the data breach on their blog," Bono Mack said. "That's right. A blog. I hate to pile on, but -- in essence -- Sony put the burden on consumers to 'search' for information, instead of accepting the burden of notifying them. If I have anything to do with it, that kind of half-hearted, half-baked response is not going to fly in the future."

In the letter, Hirai says Sony first learned of the breach on April 19, then shut down the PlayStation Network on April 20 due to an "external intrusion." However, Sony did not inform PSN users until six days later that personal data and possibly credit card information was compromised.

On Monday, the company's online branch, Sony Online Entertainment, revealed it had shut down all services due to an intrusion. The breach exposed the personal data of 24.6 million SOE subscribers as well as some financial information.

"Throughout this challenging period, (Sony employees) acted carefully and cautiously and strove to provide correct and accurate information while balancing concerns for our consumers' privacy and need for information," wrote Hirai.

In a summary of its response on the official PlayStation blog, Sony said "intruders had planted a file on one of our Sony Online Entertainment servers named 'Anonymous' with the words 'We are Legion.'"

Hirai said in the letter that Sony is still not certain whether credit card data was swiped during the PSN breach. Earlier this week, Sony dismissed reports that it had been offered a list of credit card numbers for PSN users to purchase.

Hirai also reiterated the additional security measures Sony has taken since the breaches, including enhanced data protection and encryption, more firewalls and the hiring of a chief information security officer.

Sony has not indicated when SOE services will return. On Sunday, Sony said some PlayStation Network services would be back online this week.

Readers can view Hirai's full letter to Congress here.