China's television watchdog is to crackdown vulgar and illegal commercials to further "purify" the screen and create a "green" environment for the public, especially children.

The State Administration of Radio, Film and Television (SARFT) will tighten its control on adverts exaggerating the efficacy of medicines and vulgar advertisements with sex-explicit contents, said Ren Qian, deputy director of the SARFT social management bureau, at a national meeting in Yangzhou, a city in eastern Jiangsu Province on Wednesday.

"Though some medicine commercials have been licensed, when being broadcast, their original content was changed, which misled consumers and broke the law," he said.

He added that ads concerning adult products such as female underwear should only be aired at midnight.

Ads for products such as medicine for beriberi or hemorrhoids, and female hygiene products are also banned from being shown during prime time, which falls on 6:30 a.m to 7:30 a.m., 11:30 a.m. to 12:30 a.m., and from 6:30 p.m. to 8 p.m. each day, according to Ren.

"Authorities should also step up monitoring on ads that don't violate the laws but are deemed 'vulgar' and will have negative social impact," he said.

He gave two examples of such ads, "naobaijin" and "huangjindadang" in Chinese, both were nutrient products of the Shanghai Goldpartner Biotech Co Ltd.

The ad of "huangjindadang" boasts that it is a good gift to teachers, relatives and bosses.

"This ad will have an extreme negative influence on the minors, " he said. "the government should ask the company to switch to another version for broadcasting."

As to the scrolling adverts during relay of programs, Ren urged that government to follow the interim regulations on control of radio and TV advertisements, promulgated in 2004.

It prescribes clearly that the integrity of relayed programs should be ensured and self-arranged advertisements or interference with original advertisements are not allowed.

Ren also said that those broadcasting stations who refuse to rectify their wrongdoing or break the regulation more than three times within 60 days would face severe punishments including a suspension of airing or the loss of licenses.

Earlier this month, about 30 radio and television stations, including China Radio International, China Central Television and Beijing Television, jointly issued a self-discipline pact, vowing not to broadcast ads which may produce negative social effects.