Shanghai plans to set up a citizen advisory panel to prevent advertisers from erecting billboards featuring scantily clad women and other images that might offend local sensibilities.

The move follows a series of recent complaints over a huge billboard in the Xujiahui area that displayed the bare thigh of a Hong Kong pop star who was selling skin-care products.

The billboard was taken down after authorities discovered that the space had been approved for a public service ad and that an improper switch had occurred.

To prevent such problems in the future, the Shanghai Industrial and Commercial Administrative Bureau is preparing to set up a council involving residents, legal experts and industry representatives this year to weed out potentially offensive and misleading advertisements.

"It's sometimes difficult to decide whether ad content is improper because different people have different standards," said the bureau's advertisement division chief, Miao Jun.

State regulations require that female images used in advertising must be "healthy and positive" and help foster sound morals among young people - stipulations that are vague at best.

More rigid internal guidelines existed in the industry in the 1990s, prohibiting women shown in ads from wearing skirts or shorts ending above knee level. But insiders said those rules are seldom enforced today, as society has become more open-minded.

In most cases, bureaucrats make individual judgments about whether an image will offend the public.

Ads that run afoul of public taste are not always sexually suggestive. In another case last year, a little boy in Putuo District was frightened by a cosmetics spot on TV that featured a woman who appeared to zip off her skin. The ad gave the boy nightmares, and his mother complained to the consumer commission, to no avail.

Xu Hong, director of the Shanghai Advertisement Monitoring Center, said that while some complaints have been raised, the problem of offensive advertising is not a large one.

The advisory council will make it even less of a bother.

The group will be used to arbitrate questionable material. It will also help authorities make judgments about exaggerated claims and misleading statements in advertising for medical services and equipment and health tonics.