Prime Minister Malcolm Turnbull has moved to alleviate worries about the security of personal details gathered in the Census, after independent senator Nick Xenophon called for the national survey to be delayed over privacy concerns.

Key points: Malcolm Turnbull says personal details gathered in Census are protected by law

Malcolm Turnbull says personal details gathered in Census are protected by law PM says the ABS has "always protected people's privacy"

PM says the ABS has "always protected people's privacy" Nick Xenophon wants survey delayed amid access concerns

The compulsory survey, to be carried out on August 9, has been under fire from privacy advocates since the Australian Bureau of Statistics (ABS) announced it would, for the first time, retain all the names and addresses it had collected "to enable a richer and dynamic statistical picture of Australia."

The Australian Privacy Foundation last month called on the ABS to stop using people's names for data analysis, but Mr Turnbull said on Wednesday the organisation "always protects people's privacy".

"The security of their personal details is absolute and that is protected by law and by practice," he said.

"That is a given."

ABS chief statistician David Kalisch said the organisation had "never had a privacy breach with Census information".

David Kalisch said the ABS had never had a security breach with Census information ( ABC: Marco Catalano )

Mr Kalisch said privacy concerns were raised every time a Census was conducted.

"The ABS has the best security features," he said.

"We've never had a privacy breach with Census information and we do secure the information somewhat differently … These days we can keep names separate from address and separate from other Census content, in three separate computer systems and never brought together."

When asked if he believed this year's Census had been handled poorly, Mr Kalisch responded that "we're well ahead of where we thought we would be".

Process at risk of becoming 'shemozzle': Xenophon

Concerns have also been raised over the changes in completing the form, with independent Senator Nick Xenophon calling for the Government to delay the Census amid confusion over the shift to an online form.

This year Australians have the option of either filling in the Census online using a 12-digit identification number, or calling a phone hotline to request a paper copy.

However, some people who are seeking a paper form have been unable to get through on the phone line, as it struggles to keep up with the huge demand.

Senator Xenophon and his party's Member for Mayo Rebekha Sharkie said the transition had been mishandled.

He said the process was at risk of becoming a "shemozzle" and some people would not fill in the national survey because of their concerns.

"If the Census is meant to be a snapshot of Australia on [August 9], I wonder if it'll end up being more like timelapse photography that's very blurred — because it seems that there is a lot of chaos and dysfunction in the way it is rolled out," he said.

"This census may go down in history, for the unenviable statistic, that there will be a record number of Australians that won't be participating in it."

Wilkie seeks assurances on fines

Independent MP Andrew Wilkie also issued a statement, citing a "broad feeling of confusion in the community".

"I do not doubt the importance of the Census and I commend the vast majority of ABS staff for doing the very best they can," he said.

"But the Government needs to step up and listen to the concerns in the community and provide an assurance that no one will be fined if they haven't been able to complete the census."

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 6 minutes 38 seconds 6 m Confusion and anger over Census

Labor frontbencher Andrew Leigh defended the process, but called on the Government to support it.

In a statement, Dr Leigh said the Census should be a "first order issue for the Turnbull Government".

The Census office has carried out extensive testing of its technology to see if it can cope with demand.

It said the data required to fill out the Census was small, and should not add too much pressure on internet providers.

'Australians should be worried'

Nigel Waters, Australia's former deputy privacy commissioner, was hired 11 years ago by the ABS to investigate whether keeping identifying data was a good idea.

"What they are now doing is breaking the compact or the deal that they have had with the Australian people for the last 100 years, which is that in exchange for giving them very sensitive information — including about your relationships, your health, your financial circumstances — their part of the deal was to make sure that that information would be de-identified as soon as possible," he told 7.30.

Liz Allen says she is shocked by the conspiracy theories around this year's Census ( Supplied: ANU )

Dr Mark Gregory from the RMIT School of Engineering said "Australians should be worried" about the ABS collecting their personal information.

"They can't guarantee the security of the information. We know that Australia does not have mandatory data breach reporting laws and until those laws are put in place and security improved both within government and business then Australians have a great concern about the privacy of any information that they provide," Dr Gregory said.

But for social researchers like Liz Allen, a demographer from the Australian National University, more detailed Census data means better research and better targeted government policy.

"The consequences of boycotting or sabotaging census data — putting aside the fact that you could be fined and face prosecution — is that the data won't truly reflect Australia," Dr Allen told the program.

"Australians rely heavily on data to provide an evidence base. We don't want to build a road to nowhere, I think everyone would agree that evidence-based policy is the way to go."