The Shanghai Labor and Social Security Bureau is worried about the number of job seekers offering to work for free in order to get their foot in the door at a company in the hopes of eventually being offered a paid position.

The bureau reminded employers and job seekers yesterday that such agreements are illegal, as the city's labor law sets the minimum wage at 6 yuan (75 US cents) an hour.

"We understand that graduates are eager to find a job, but the country's labor law states that employees should be paid according to their performance," Lu Tingfei, an official with the bureau, said.

"Any non-paid probationary contract would be considered invalid, even if the employee agrees to it," Lu said.

While the bureau says it is impossible to get exact numbers on how many recent graduates are offering to take unpaid jobs to impress potential employers, anecdotal evidence suggests the number is on the rise.

During a citywide job fair for privately owned companies last week, several recent university graduates asked about working for free for a short period of time.

They simply asked that companies evaluate them after a short period, and offer a paid job if they prove to be good workers.

Such agreements often don't work out for the unpaid employees, according to the bureau.

For instance, an advertising major surnamed Lin applied to work for free at a local ad company last summer.

"At first I told myself that it's nothing to work for free for several months," Lin said. "Job competition is so fierce nowadays, low salary and even free work is worthwhile so long as it could earn me an opportunity."

However, the free internship went on for nearly one year, but the employer never offered Lin a paid position. Human resource managers say that offering to work for free isn't necessarily the best way to prove you are eager to work.

"People who offer to do non-paid probation work tend to leave HR managers with the impression they have poor working ability or lack confidence. It is impossible for companies to trust this kind of person," said Li Shanshan, HR manager at WindnMoon Entertainment Co Ltd, a South Korean-invested company in the city.