Australia's prime minister says his country's first attempt to conduct a census online will resume two days after it shut down due to system failures that left it vulnerable to cyberattack.

Prime Minister Malcolm Turnbull on Thursday blamed failures of the Australian Bureau of Statics and systems provider IBM after the national survey was taken offline on Tuesday night. It was removed because a digital shield failed to block traffic from a fourth denial-of-service attack that came from somewhere overseas.

Turnbull says the system failures have been corrected at his personal direction under the supervision of government's top electronic security and intelligence agency, Australian Signals Directorate. The census will go back online sometime on Thursday.

Turnbull says there are "very big issues" for both the Bureau of Statistics and IBM.