Communications Minister Stephen Conroy says a technical error is to blame for the black-listing of a website with artist Bill Henson's photographs on it.

Henson's photographs have attracted controversy because they often depict naked teenagers.

Senator Conroy has told ABC 1's Q and A program the Classification Board rated the photographs PG.

He says a technical error by the body that controls the black-list, the Australian Communications and Media Authority (ACMA), is to blame for the black-listing.

"It was actually cleared by the Classification Board so it shouldn't have been on the list," he said.

"I've asked ACMA in the last few hours to go through their entire list again to see if there are any other examples of this."