Millions of Australians were met with error messages on Tuesday as they tried to complete the online census as the ABS system descended into meltdown.
The ABS apologised for the mass outage and initially claimed the website had been overloaded by users.
They have since backtracked and confirmed the site was hacked.
In the past Australian government websites have been attacked by Chinese hackers.
A number of digital assaults on the census website began during the day on Tuesday and were repelled.
ABS previously said the outage was due to the high volume of users accessing the site, but confirmed on Wednesday the site had been hacked
The ABS census site is expected to be back on line around 9am on Wednesday, but some have already claimed on social media that the recent hacking has put them off completing it
But the frequency increased as the evening neared and many Australians trying to reach the census site after 7pm couldn’t connect.
It was at this point the ABS said it began the process of shutting down the site.
The ABS released a statement around 11.30pm on Tuesday advising the websites was unavailable.
It’s reassured Australians they won’t be fined for not completing the census on Tuesday.
The ABS census site is expected to be back on line around 9am on Wednesday, but some have already claimed on social media that the recent hacking has put them off completing the survey.
Thousands have taken to social media to slam the ABS for the botched census.
‘Hackers crashed the census site but don’t worry, you have until Sept 23 to enter your personal info so it can be hacked at a later date,’ on Twitter user wrote.
Another tweeted: ‘We’ve never been hacked’ less than 15 hours after peak census… ‘we got attack’ – good job idiots.’
‘Dear ‘ABSCensus ‘Hackers Hacked The Census’, if true, reflects on your woeful preparation, design & implentation.
‘My census answers were also hacked. My name is definitely not DingDong McChaddlepops.’
The Australian Bureau of Statistics has now launched a joint investigation with the nation’s defence intelligence agency into the assault
The 2016 census has been fraught with contention after it was discovered the ABS would be holding onto data for four years instead of the standard 18 months.
Labor now wants the minister responsible for the botched census, Michael McCormack, to resign after the foreign cyber attack.
Shadow assistant treasurer Andrew Leigh is furious the government failed to properly explain its decision to take the national survey online.
‘If you can’t get the census right how can you govern the country,’ he told ABC radio on Wednesday.
Australians have until September 18 to complete the paper forms and September 23 online – based on those in your dwelling on the night of August 9.