At least seven senators face being fined after vowing not to provide their names on their census forms tonight.

Key points: Senators face $180-a-day fine if they do not complete census, David Kalisch says

Senators face $180-a-day fine if they do not complete census, David Kalisch says Privacy advocates say "statistical linkage key" could link individual to future surveys, even if name is deleted

Privacy advocates say "statistical linkage key" could link individual to future surveys, even if name is deleted Mr Kalisch says ABS has unblemished record keeping data safe

The names and addresses of Australians will be kept for an additional two-and-a-half years, sparking fears from privacy advocates.

Senators from the Greens, as well as fellow crossbenchers Nick Xenophon and Jacqui Lambie, have threatened not to write their names and addresses due to security concerns.

They face a fine of $180 a day if they do not complete the survey.

David Kalisch from the Australian Bureau of Statistics (ABS) said it was "certainly possible" the federal politicians could be prosecuted.

"A number of them (senators) made comments to date," he said.

"We'll just see what happens. We obviously want all Australians [to answer in full] and we hope with the information were providing to them now … that they might change their minds.

"I would of preferred that some public figures had sought the facts from the ABS before they made a number of their public comments, as we could of corrected a number of misunderstandings."

Scott Ludlam said the "statistical linkage key" could "follow you for life". ( ABC News: Nick Haggarty )

Greens senator Scott Ludlam has criticised the ABS's handling of the issue, which has created headlines in the days leading up to the census.

"The [ABS] has nobody to blame but itself for what's unfolding," Senator Ludlam said.

He also said a "statistical linkage key" — created using the details of Australians participating in the census — could "follow you for life".

Privacy advocates say the key could be used to help potentially link individual Australians to future surveys, even if the original name had been deleted by the ABS.

The Greens have called on the ABS and the Federal Government to waive the fines for anyone who refuses to provide names and addresses in their census form.

Personal information will be safe, ABS says

Names and addresses will be kept by the ABS for four years, up from 18 months.

Mr Kalisch said this would give decision-makers extra time to look over the data to inform policy.

"It just enables us that little bit more time to provide more information to the Government, to decision-makers, but also provide it in a way that does inform public policy," he said.

But he said the additional time would not jeopardise the security of the public's personal details.

"The ABS shares the same concern for your privacy as privacy advocates and has an unblemished record keeping your census data safe as a result of the legislative protections, our systems and our culture," he said.

"Your information cannot be identified outside the ABS and is safe inside the ABS."

Small Business Minister Michael McCormack said in a statement the information would be protected by the "strongest encryption technologies available".

"The ABS has assured the Government all possible measures have been taken to protect the integrity of data provided in this year's census," Mr McCormack said.

"The collection of names and addresses in the census has been a feature of all past censuses, dating back to 1911, in order to ensure the quality and accuracy of important official statistics."

Science and Industry Minister Greg Hunt dismissed the concerns of Senator Ludlam and others regarding the use of the census data by the ABS.

"I'm not aware that they're complaining about online banking, medical records, any of the area," Mr Hunt told Melbourne radio station 3AW.

"It feels as if Scott Ludlam has been reading too many Robert Ludlum conspiracy novels."