Australia will launch an official investigation into how the country's nationwide five-yearly census was bungled due to a hardware failure and cyber attacks, the government said Wednesday.
More than two million people had entered census information online on Tuesday before the website was taken down as a precaution by the Australian Bureau of Statistics, after a number of hacking attacks.
Prime Minister Malcolm Turnbull said the data was safe, despite the denial of service attacks, and that the bureau had an "unblemished record" on data security.
He said proper defences were in place, but a computer hardware failure led to the decision to temporarily take down the site. Trumbull said there would be a review into the incident.
Alastair MacGibbon, the prime minister's cyber security adviser, said the attack came from American computer networks, but that did not mean the attacker was US-based.
"A denial of service is not a breach. It's not designed to take data. A denial of service is designed to frustrate," MacGibbon said.
The website was still down on Wednesday afternoon.
Opposition leaders have asked for a Senate inquiry into the failure. They have also called on the census minister to resign.
About two-thirds of Australia's 23 million people are legally required to give the Australian Bureau of Statistics information about their homes, religion and income in the national questionnaire.
Now they can complete the census by September 23.
The census was mired in controversy after some politicians issued boycott calls Monday over fears surrounding data privacy and storage.