Privacy advocates are calling on the Australian Bureau of Statistics (ABS) not to collect names of individuals in next month's census, due to privacy concerns.

For the first time, the ABS will keep Australians' names and addresses on file for four years instead of 18 months.

Meanwhile, it has emerged the ABS has been using people's names and addresses to cross-reference data with records kept by other Australian departments since 2006.

Before this, they were largely used for administrative purposes, to ensure everyone completed the census.

The revelations have prompted concern on talkback radio and social media, with some people declaring they will boycott the census because of the changes.

The Australian Privacy Foundation is calling on the ABS to stop using people's names for data analysis.

"We all gave our names in good faith, thinking they'd be deleted," said the foundation's vice-chair Kat Lane.

"We've now since found out they're not being deleted at all, they're being stored and made into unique identifiers.

"We don't want the ABS to have very sensitive personal details like names. We want them to be deleted."

Security 'highest priority' for ABS

Head of Census with the ABS, Duncan Young said there was wide consultation with the public before the changes this year.

He said extending the amount of time that names were kept on file to four years would give the ABS more time to carry out its work.

"The ABS has consulted widely on these changes we're making in 2016 and we know by making these changes we can further enrich the lives of Australians by helping governments make better choices," Mr Young said.

Since 2006, 5 per cent of respondents have been tracked from census to census, to analyse changes over time.

Mr Young said people's names were replaced with "anonymising" computer codes by computers collating census data, and that no workers ever saw names connected with personal information.

"The security of ABS systems is one of our highest priorities, so we've worked very hard to make sure there are many layers of security in place," he said.

'Invasion of privacy'

But former Australian statistician and head of the ABS, Bill McLennan, believes the changes are illegal.

He said that under the Census Act, Australians were not compelled by law to provide their names to the ABS.

"I think it's a significant invasion of privacy, and the ABS shouldn't do it," he said.

Anyone who does not complete the census or is found to have answered dishonestly, faces a fine under the Census Act.

The head of The Statistical Society of Australia, Dr John Henstridge, said he did not believe the ABS did enough to consult with the community.

"I think it probably needed more of a publicity campaign about this and being a bit more open," he said.

"If people don't want to cooperate with the census because they are concerned about how the data might be used then that is a real concern."

The 2016 census will be held on August 9.