Australian businesses on high alert for global cyber attack.

The Australian arms of global firms including Cadbury owner Mondelez International are scrambling to protect their computer systems amid a global cyber attack.

Mondelez, the Spanish food giant that owns the Cadbury chocolate factory in Hobart, and international law firm DLA Piper, which has offices across Australia, both said their global IT systems had been brought down.

Their computer systems may have been hit by the so-called “Petya” or “Golden Eye” cyber attack that began overnight in Europe and experts have likened to the ransomware virus Wannacry that hit more than 300,000 computers in May.

The latest virus freezes computers until users pay a ransom in Bitcoin.

The federal government is urging local firms and households that suspect they’ve been hit to report it to the Australian Cyber Security Centre.

Banks, airports and the state power company in Ukraine were among the first to be hit in the latest attack, followed by Russia’s biggest oil firm Rosneft, Danish shipping giant Maersk, US drug maker Merck, London-based advertising firm WPP and French construction firm St Gobain.

“The Mondelez International network is experiencing a global IT outage,” the food company said in a statement.

“Our global special situations management team is in place, and they are working to resolve the situation as quickly as possible.”

In a statement on its website, DLA Piper said it was dealing with a “serious global cyber incident”.

“We have taken down our systems as a precautionary measure which will mean you are currently unable to contact us by email or landline,” the company said.

Australia’s cyber security minister Dan Tehan said the fresh attack was a wake-up call for Australian businesses to regularly back up their data and install the latest security patches.

Local authorities were doing everything possible to prevent the virus spreading here, he said.

“We are aware of the situation and monitoring it closely, we are in contact with our Five Eyes partners,” he said.

“If your business has been infected you should isolate the affected computer from your network to prevent the software spreading and use backup data to restore information.”

Alastair MacGibbon, the special advisor to the prime minister on cyber security, warned computer users not to be tempted to pay those demanding a ransom in exchange for unlocking their computer.

“Our advice … would be you don’t ever pay a criminal,” he told ABC radio.

“With Wannacry it was a very unsuccessful enterprise for whoever started it. It actually generated tiny sums of money. So it hasn’t been good for the crooks.

“The best advice is to try to avoid being a victim in the first place, which is why we say back up your data.”