The four-hour strike at Qantas which was supposed to start at 7 a.m. in many airports began 3:30 a.m. The early start was caused by the air carrier's alleged lockout of the 3,800 striking baggage handlers, ground staff and caterers.

"When we talk about passengers and how they were inconvenienced, everyone has to remember that from 3:30 a.m. until 7 a.m. Qantas has been on strike, not the workers," Transport Union Workers (TWU) spokesman Mick Pieri told The Wall Street Journal.

Qantas spokesman Luke Enright denied the airline locked out the employees since they would be paid.

"(Workers that) had come to work and advised they would be striking... (were told) we can't cause more disruption to passengers by having you come on and off shift.... We will pay you the hours but you won't be required to work," Mr Enright said.

The labor dispute over pay increases and job security has led to the cancellation of 28 flights and delays by up to 35 minutes for 27 more trips. Mr Enright said the air carrier expects to resume normal operations by lunchtime.

The industrial action has affected about 7,000 passengers and is expected to be felt for two more days due to a 48-hour ban on TWU union workers from performing certain duties outside their main task.

To minimize the impact of the strike, Qantas flew wider-body aircraft and assigned management staff to perform the duties of striking workers.

The TWU-led strike coincided with a similar action by pilots and engineers unions.

The TWU is seeking a 15 percent pay increase spread over three years and more job security.

"They may it sound like we are asking for the world. We are asking for job protection and the right to go to an independent umpire... we are still working under a Work Choices document and that's why we're having the problems," Mr Pieri added.

Mr Enright estimated that 90 per cent of Qantas' flights flew on schedule, but 150 flights have been affected. Canceled were 11 trips from Sydney, 10 from Melbourne, four from Brisbane, two from Canberra and one from Adelaide.

Qantas group executive Olivia Wirth called on the TWU to return to the negotiating table. She pointed out the airline employees are compensated well. In the case of baggage handlers, Ms Wirth said Qantas pays them 12 percent higher than their counterparts at Virgin Australia.