TOKYO • A United Nations special envoy has called on Japan to ban cartoon images featuring "extreme" sexualised images of children, after Tokyo last year fell into line with other G-7 nations by criminalising possession of child pornography.

But graphic images of paedophilia in manga comic books remain legal under the new law, which went into effect this summer, while books and videos of real children in sexually provocative poses are still widely available - and legal.

Campaigners had long urged Japan to toughen its stance on child pornography, complaining it was a major source of the material globally.

"When it comes to particular, extreme child pornographic content, manga should be banned," Ms Maud de Boer-Buquicchio, the UN's special rapporteur on the sale of children, child prostitution and child pornography, told reporters yesterday as she wrapped up a week-long Japan tour.

But she acknowledged the challenge in "finding the right balance" between artistic freedoms and the need to protect children.

"I accept that the freedom of expression argument should outweigh, should prevail when it comes to adult pornography," she said.

Despite calls for manga imagery to be included in the new rules, there was strong resistance from manga artists, free-speech advocates and publishers, who said it would impinge on freedom of expression and allow the authorities to make arbitrary decisions about art.

Ms De Boer-Buquicchio criticised the law for being riddled with "numerous loopholes" and lashed out at so-called "child erotica", saying kids were being exploited.

The still-legal offerings feature photos and other materials depicting half-naked children in skimpy outfits, such as tiny bikinis.

DVDs or photo books of child erotica are readily available online and at stores in Tokyo, including in the city's well-known Akihabara district.

AGENCE FRANCE-PRESSE