Some high-tech firms may be underreportingcyber attacks such as those suffered by Sony Corp., Google Inc. and others in recent weeks, Reuters reported.

As companies such as defense giant Lockheed Martin Corp. also work to fend off hackers, the stigma associated with breaches in computer security is leading some to remain tight-lipped about potential threats.

“One of the reasons we do not know the scale of this is that organizations are embarrassed to reveal the impact,” said Sir Michael Rake, chairman of BT Group plc.

Some firms might not understand the extent of exposure they face. Others employ corporate intelligence specialists who have been sworn to secrecy by firms fearful of revealing the information to corporate partners, investors or competitors.

Sony recently suffered damage to its reputation, when the personal details of millions of PlayStation users were compromised. Most specialists think the most recent attacks are just the tip of the iceberg and are calling for more transparency and communication.

“Everyone is getting attacked, but no one is talking about it,” said Vartan Sarkissian, CEO of security firm Knightsbridge Cybersystems. “If you can’t value the cost of the attacks, you don’t know how much you can spend to prevent them. … We need a way of sharing information anonymously.”