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The boss of Sony has fired back at critics, insisting it did act quickly enough to tell users about a security breach of its PlayStation network.

Sony chief executive Howard Stringer said most security breaches go unreported, and that only 43% of firms "notify victims within a month".

"We reported in a week. You are telling me my week wasn't fast enough?"

Last month, account information of more than 100 million customers was compromised in a massive cyber attack.

On 20 April, the Japanese electronics giant was forced to shut down its PlayStation network and other services.

Some gaming analysts have criticised Sony for not being quick enough to alert customers about the breach.

"This was an unprecedented situation," Mr Stringer said, speaking publicly for the first time since the security breach.

The attack is considered the biggest in internet history.

Mr Stringer's remarks are a change in tune from two weeks ago when senior executives bowed to apologise to the company's customers.

Sony is still assessing how much the breach might cost the company.

"There's a charge for system being down, a charge for identity theft insurance," said Mr Stringer.

"The charges mount up but they don't add up to a number we can quantify just yet."

Sony will report its full year results on 26 May.