US aerospace giant Boeing is under "continuous" cyber attack but there has been no breach of its databases, a senior executive said.

Boeing headquarters in Chicago, Illinois

The admission by Dennis Muilenburg, the chief executive of Boeing Defense, Space and Security, comes as Japanese electronics giant Sony recovers from a series of online incursions while Google also said it has been hit.

"We, as are other global enterprises, are under a continuous state of cyber attack and cyber probing," Muilenburg said on Friday.

"We recognise the reality of global business today, is that cyber attacks are part of business and we\'ve been prepared for that so this is not a surprising environment to us," he told a media briefing in Singapore.

Muilenburg did not want to mention how often the attacks took place or the people behind it but said Boeing\'s investment to protect its systems from hackers has paid off.

"I can tell you that the defensive capabilities that we\'ve built up are very effective, and give us confidence and our enterprise is secure because of that investment," he said.

Sony last month was forced to shut down some of its online services after the details of more than 100 million account holders were stolen.

And on Thursday hackers claimed to have compromised more than one million passwords, email addresses and other information from SonyPictures.com.

In Thursday\'s attack the hackers posted lists of thousands of the pilfered Gmail, Hotmail, AOL, Yahoo and other email addresses and passwords on Pastebin, where they were publicly accessible.

Earlier this week Google said a cyber spying campaign originating in China had targeted Gmail accounts of senior US officials, military personnel, journalists and Chinese political activists.