South Australia's Attorney-General has defended tougher laws on political comment made on the internet.

During election periods, anyone posting comment or blogs must publish their real name and postcode.

Michael Atkinson says it has long been a requirement that newspapers verify personal details for letters published during election periods.

He says the new law, which has applied since early last month, ensures the public's right to know.

"[It's really about] the right to know who's making a comment during an election period," he said.

"It will only apply to newspapers and extensions of newspapers.

"All it is ... is a re-formulation of the very old rule which has applied throughout our lifetimes that if in the election period, and only in the election period, if you write a letter to the paper calculated to affect the result of the election then you have to do so under a real name and a real address."

Mr Atkinson says television and radio has always been regulated by the Commonwealth and it is most likely that comment on websites such as the ABC's would fall into that category.

'Avoid any criticism'

The editor of The Advertiser newspaper Melvin Mansell is outraged by the Attorney-General's move.

"What the Attorney-General is trying to achieve here is to avoid any criticism whatsoever of government policy," he said.

"The clear implication is that if you show enough dissent he's going to take action against you."

There is concern that the Government's powers may extend to political comment made on social networking sites such as Facebook and Twitter.

A coalition of major newspapers has branded the new law as draconian censorship of public comment.

SA is about to enter a formal campaign period ahead of its state poll on March 20.