WA-based shipbuilder Austal, which has built patrol vessels and frigates for the Australian and US  navies, has revealed that it has been the subject of a cyber security breach and extortion attempt.

Austal has confirmed that the hackers got access to drawings and designs of many of its Australia ships, but maintains that so far there is no evidence that information affecting national security has been stolen.

Some staff e-mail addresses and mobile phone numbers were among the material accessed, according to the statement. It said it appears that the offender/s have tried to sell some of the stolen material online “and engage in extortion”.

But it added that Austal “has not – and will not – respond to the extortion attempts.”

The Federal Police and Australian Cyber Security Centre have been informed and are said to be investigating.