Modelling agencies usually look for their 'targets' in busy places like MTR stations and shopping arcades, and even on the street.

Representatives of these companies often promise to arrange singing, filming or karaoke contracts for their 'stars'.

If the 'targets' show any signs of interest, the representatives then persuade them to pay a deposit for auditions or photo-taking sessions which can cost between $1,000 and $40,000.

'These employers promise to find jobs for young people and guarantee to refund their deposits if they fail to do so,' said Chan Wing-kai, the Consumer Council's chief complaints and advice officer.

However, in most cases the firms failed to find employment for the youths, and even if they did, the youths' salaries were cut to pay for 'training sessions' offered by the companies, Mr Chan said.

There are telltale signs that students can look out for in these dubious employers, Mr Chan said.

'Genuine professional modelling agencies never ask young people to pay for auditions,' he said. 'Neither will they keep their identity cards, credit cards or cheque books.

'Students should always seek the advice of their parents and friends before they sign any agreement or contract.' Unscrupulous investment firms usually ask their young employees to put a sum of money into an investment account. These sums can range from several thousand dollars to as much as $50,000.

The employees are then asked to sign an agreement that says the company would not be responsible for any loss in the investment.

'These firms will tell the students that they have lost their money and will persuade them to invest some more. In the end, the youngsters will lose all their money,' Mr Chan said.

He added that students should explore the nature of a job before committing themselves.

'Salary should not be their only concern,' he said.