Union 'concerned' by Flight Centre bullying allegations

The Australian Services Union says it has been concerned for sometime about allegations of underpayment and unreasonable pressure on Flight Centre employees.

The Australian Services Union says they are 'deeply concerned' for Flight Centre employees. (AAP)

Unions say they're "deeply concerned" about claims of the underpayment and bullying of staff at travel giant Flight Centre.

The Australian Services Union on Thursday it had raised the issues previously with the Fair Work Ombudsman but more evidence had been brought to light in an investigation by the ABC.

"We are currently in discussions with Flight Centre, where we aim to significantly improve workers' pay and conditions and bring about significant change," the ASU said in a statement.