Australia's census website has been shut down by overseas hackers, stopping thousands of people from taking part.

The Australian Bureau of Statistics (ABS) website was closed as a precaution on Tuesday evening after being targeted in four separate attacks in quick succession.

ABS head David Kalisch said: "It was an attack, and we believe from overseas."

He said he believed it was a deliberate act of sabotage but warned: "The Australian Signals Directorate are investigating, but they did note that it was very difficult to source the attack."

The site was taken down just after 7.30pm as a precaution to "ensure the integrity of the data".


A message on the ABS website said it had been subjected to four different denial of service attacks, which sees people blocked from accessing website.

Mr Kalisch told the ABC: "The online census form was subject to four denial of service attacks.

"The first three caused minor disruption, but more than two million forms were successfully submitted and safely stored.

"The scale of the attack, it was quite clear it was malicious. Steps have been taken during the night to remedy these issues and I can certainly reassure Australians that the data they provided is safe."

We apologise for the inconvenience. The 2016 online Census form was subject to four Denial of Service attacks of varying nature & severity. — Census Australia (@ABSCensus) August 9, 2016

But later Michael McCormack, the minister responsible for the census, said it was "neither an attack nor a hack".

Prime Minister Malcolm Turnbull said it was a "confluence of events" that led to the outage.

An investigation has been launched by the country's privacy commissioner Timothy Pilgrim.

Attorney-General George Brandis said that "individual privacy" had been protected.

Two-thirds of the population were expected to fill out this year's census online, rather than on paper.

The census is carried out every five years, and those who do not take part can face fines.

However, the ABS said no one will be fined for late submissions this year, and people will have until 23 September to complete the process online.