More than 11,000 Qantas passengers will have their travel plans affected by industrial action at three major airports today.

Qantas says 80 domestic and international flights will be cancelled, delayed or brought forward when engineers walk off the job for four hours this afternoon in Sydney, Brisbane and Melbourne.

The Australian Licensed Aircraft Engineers Association says it wants a 15 per cent pay rise and better job security.

But Qantas says its maintenance engineers are the highest paid in the world, and current demands are unreasonable.

The carrier says it wants to return to the negotiating table as soon as possible.

The strike begins at 3:00pm AEDT (4:00pm AEST).

Qantas estimates the latest industrial action would take the total number of passengers affected by recent strike action to 46,500.

More delays at Australia's international airports are likely on Thursday when Customs inspectors stop work over a pay negotiation.

The Community and Public Sector Union has rejected the Federal Government's offer of a 9 per cent pay rise over three years.

ABC/AAP