Hundreds of Australian companies have been on the receiving end of what the US and UK allege is a Russian government-sponsored cyber attack against internet network infrastructure around the world.

Britain's National Cyber Security Center, the US Department of Homeland Security, and the FBI issued a joint alert on the attacks, which began in 2015 and impacted many Australian companies in 2017.  The state-sponsored hackers targeted the CISCO routers that form a key part of the internet infrastructure.

Defence Minister Marise Payne doesn't believe any critical information was compromised: "The Australian Cyber Security Centre.. believes that potentially 400 Australian companies were targeted, but don't believe there has been any exploitation of significance," she said.

The FBI has "high confidence" that the hackers are using the compromised networks to spy, steal intellectual property, and "potentially lay a foundation for future offensive operations".