Virgin Atlantic is forcing hundreds of new staff each year to pay for their own criminal record checks after referring them to an employment screening firm.
New staff at the airline's call centre in Swansea have been asked to pay for the background check.
Department of Transport rules require criminal checks for air-side staff but not for other airline employees.
Virgin Atlantic says its recruitment process has to be extremely thorough.
The airline employs around 8,500 people worldwide and recruits hundreds of staff in the UK each year.
The issue was highlighted after a recent graduate contacted BBC Radio 4's Money Box programme.
Having recently been offered a job in Virgin Atlantic's call centre, she says she was contacted by a firm called Procius, which does pre-employment screening on behalf of Virgin Atlantic.
The graduate, who did not want to be identified, says she was asked to create an online profile with Procius.
"Before the online profile could be completed, I was requested to pay to cover the costs of the reference check.
She told Money Box there was no mention of a fee when Virgin Atlantic first contacted her about Procius, and she did not like having to pay the fee before really understanding what the check was for.
However, she felt obliged to pay the fee if she wanted to secure the job she was being offered.
Virgin Atlantic and Procius say the was for a criminal record check.
Procius insists that this is made clear when employees are asked to make the payment.
Such checks are often outsourced to agencies by big firms who want to check the credentials of people who they offer jobs to.
The Trades Union Congress believes the number of firms requesting checks, either directly or through pre-employment screening firms, is growing.
Helen Reid, the TUC's senior employment rights officer, says firms should be paying the fees to cover such checks, not newly employed staff:
"They should be footing the bill," said Ms Reid.
"It's unreasonable to expect people - particularly who've faced unemployment for a long period of time - to pay in order to be considered for a job."
The graduate undergoing the check following her job offer from Virgin Atlantic says that if the company wanted to screen her, it was in a much better position to absorb the cost than she was:
"I have been left feeling that I am being taken advantage of by companies who are well aware of how difficult it is to find employment, and have realised that they can charge ridiculous fees for even the simplest reference check."
In a statement Virgin Atlantic said: "Safety and security within the airline industry is of paramount importance and Virgin Atlantic has to be extremely thorough throughout the recruitment process.
"In common with many other employers, we ask all new employees to pay a fee for a criminal record check."
The requirements of other employers in the airline industry varies.
British Airways says air-side staff who require a criminal record check have to pay themselves, whilst BMI says it pays for its staff to get their security clearance.
Servisair, the ground handling firm, says it asks staff to pay themselves but then refunds them when they start working for the company.
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