The ABS was forced to bring down the online census on Tuesday night, claiming the site was the subject of 4 denial of service attacks.

Despite providing assurances in the leadup to census night that the site would be able to cope with up to 1 million submissions per hour, difficulties were reported on social media from around 5pm.

In a statement on Wednesday morning the ABS indicated that they were subjected to 4 attacks commencing from around 5:30pm. The first three attacks were graded as relatively minor, however the fourth attack was significant enough to see the census website taken offline.

The first three caused minor disruption but more than 2 million Census forms were successfully submitted and safely stored.

— Census Australia (@ABSCensus) August 9, 2016

After the fourth attack, just after 7:30pm, the ABS took the precaution of closing down the system to ensure the integrity of the data.

— Census Australia (@ABSCensus) August 9, 2016

However the ABS twitter feed was continuing to reply to users throughout the evening encouraging them to continue trying to access the census, despite the site having been voluntarily taken down.

One of the key concerns flagged by many users on social media was the potential of being fined for not completing the census. The ABS moved quickly to assure people that fines would not be issued if the census was not completed on time.

There will be no fines for completing the Census after Aug 9. There’s still plenty of time to complete the Census. Thanks for your patience.

— Census Australia (@ABSCensus) August 9, 2016

Despite the ABS using the terminology that the site was subject to an attack, the Minister responsible Michael McCormack declined to use that terminology, describing the event as an interruption designed to frustrate users.

Special Adviser to the Prime Minister on Cybersecurity Alistair McGibbon used the analogy of a truck blocking a driveway, seeking to frustrate the movement of traffic to and from the census website.

In a hastily convened press conference, Prime Minister Malcolm Turnbull sought to re-assure the Australian public that their data had not been compromised.

"I want to assure Australians that the unequivocal advice we have received from IBM, from the Bureau of Statistics, from the Australian Signal Directorate, is that their Australian Census data is safe, it has not been compromised. The site has not been hacked, it has not been interfered with - their data is safe." Mr Turnbull said.

The Treasurer, Scott Morrison, also indicated that despite the interruption there was no need to re-run the Census.

"The other issue I want to assure Australians about is there is no compromise I am advised to the integrity of the collection of the Census itself. There is no requirement of any means or any statistical reasons and credibility of those statistical collections for any re-run of this Census."

"That is the clear advice by the statistician and so the Census can proceed as it always has and the collections have always been done over a period of time referencing a particular date and I would just simply remind people, as the Minister has, to complete that form as of August 9 because that is the Census date. There is the opportunity to do that and the opportunity will be there in the not too distant future, later, when we have the advice of when that site can go up."

At the time of writing, the census website was still unavailable for users to complete online, with the last advice from the ABS being that they were attempting to restore service and would keep users updated.