A good temperament might be an obvious requirement for a city warden. Good looks? Perhaps less so.

But authorities in Chengdu, in China's south-western Sichuan province, have said they will hire only attractive young women for the law enforcement jobs, hoping it will improve their district's image.

Others say it is a blatant example of widespread looks-based discrimination that hits women harder than men. Economists have noted the "beauty premium" in many places, but employment experts say it flourishes in China thanks to inadequate laws.

The Xindu district government's advertisement stipulates that candidates must be female, aged between 18 and 23, over 5ft 2in (1.6m) tall, attractive and with a good temperament. Their contracts will end when they turn 26.

China's urban law enforcement officers, known as chengguan, have a bad reputation, with many regarding them as little more than thugs. Xindu authorities said they created the women-only team to "present the soft side".

"Their main job is to present a good image so they have to be good looking," said the human resources director of the law enforcement bureau. "And when they get older, they will get married and have children so it will not be convenient for them to do such work. Having them leave at 26 is for their sake."

He insisted it was unfair to describe them as "flower vases" – a Chinese idiom for women who are decorative but of little use. "They need a good temper and communication skills as well," he told a Chengdu news website

Lu Ying, former director of the Gender Centre at Sun Yat-sen University, said it was common for employers to pick out female candidates because they were prettier.

"The effect of looks discrimination is much bigger for women than men. What makes it worse is that for women, the job opportunities are less than for men already," she said.

"It is a very bad phenomenon. It is much worse when a government body does this because it will set a terrible example."

Private companies are certainly not immune. A current advert for a sales assistant at the Zhengzhou Electric Bike Company requires a candidate with "a smile to topple the city" and even stipulates her vital statistics: 36-22.5-36.

Li Fangping, a lawyer who has handled many job discrimination cases, said: "In the current employment law it only says that opportunities should be open and equal to everyone. It does not directly point out that employers should not include criteria such as looks and height – it is too general to be implemented."

One Shanghai cosmetic surgery hospital estimated last year that half its customers were undergoing operations for career-related reasons. Most of those were women.

But the scorn that internet users have poured on Xindu authorities suggests that others in China have little tolerance for blatant discrimination.

In 2004, the Hunan provincial government dropped its requirement for women civil servants to have "symmetrical breasts" after it was widely ridiculed.

Additional research by Lin Yi