The industrial dispute at Qantas appears to be getting personal, as Australian Federal Police investigate threats made to the airline's chief executive Alan Joyce.
The AFP is investigating specific threats made in letters sent to Mr Joyce and other senior executives.
Mr Joyce says bullying and intimidation of Qantas management is abhorrent and unacceptable and will not force a back-down or change of policy by the airline.
In a memo sent to staff yesterday, Mr Joyce labelled the letters to senior executives "cowardly" and "deplorable" and linked them to unions who are fighting the national carrier's restructuring plans.
Unions which are currently in dispute with Qantas have denied being involved.