NSW Police announced yesterday they received advice from NSW Director of Public Prosecutions Nicholas Cowdery that there was no reasonable prospect of a successful conviction.

More than 20 works confiscated from the Roslyn Oxley9 Gallery in Sydney last month will be returned.

The works attracted complaints they were pornographic because they depicted naked teenagers and sparked furious national debate. Prime Minister Kevin Rudd labelled them "absolutely revolting".

The Newcastle gallery said yesterday two of its four Henson works would remain packed away until it received official word from police, but it planned to re-install them in its administration area.

The gallery owns four Henson works. Two of the works feature naked adolescents photographed 15 years ago.

Gallery director Ron Ramsey said he was "greatly relieved" by the decision not to charge Henson or the Sydney gallery and said that commonsense had prevailed.

"Australia is known for its artistic freedom and that's what hopefully will continue," Mr Ramsey said.

He said there were no plans to hang the other two works in the near future.

The decision not to charge Henson came after Australia's Classification Board assessed the online reproduction of six of the Henson works and found one "mild and justified" and PG-rated, and the others "very mild", or G-rated.

Henson said he was reassured the law still allowed the expression of ideas.

"It is reassuring to see existing laws, having been rigorously tested, still provide a framework in which debate and expression of ideas can occur," he said.

In Canberra, Federal Police announced that no charges would be laid over Henson photographs in the National Gallery of Australia.

The actions of police were defended by Central Metropolitan region commander assistant commissioner Catherine Burn who said they were obliged to investigate complaints from the public. with AAP