Qantas blamed the engineers' strike Tuesday for the grounding of two more aircraft, which led to the cancellation of 80 more domestic flights over the next month.

The air carrier said the grounding of two wide-body Boeing 767 jets beginning Monday would cause the cancellation of trips between eastern states and Perth. That brings to seven the number of planes grounded by Qantas and to 500 the number of affected flights due to insufficient aircraft maintenance.

In terms of seats, the grounding of two jets would cause a 20,000 seat capacity reduction, which adds to the 88,000 seats already removed over the next month due to the work stoppages.

"The ongoing action from the licensed aircraft maintenance engineers union means we do not have the manpower to fulfill all of the necessary maintenance on our fleet of aircraft," Qantas Chief Executive Alan Joyce warned in a statement.

The industrial action by the Australian Licensed Aircraft Engineers Association, particularly the ban on overtime, has caused a shortfall of 60,000 manhours of maintenance and it is increasing on a daily basis. ALEAE wrote Qantas that the overtime prohibition and go-slow practices will be in place until Christmas.

"This is not a safety concern as problems are addressed before planes fly. But it is causing ongoing and unplanned disruption to our customers," Joyce added.

ALAEA Federal Secretary Steve Purvinas countered Joyce's claim that the lack of overtime and the strikes are the reasons behind the jet grounding.

"Qantas has been offered 5,000 hours a day of additional overtime, why aren't they taking it? We have called off all of our stoppages over the next two weeks. It's nothing more than a stunt because they want to seek federal government intervention," Purvinas told the Herald Sun.

Joyce said Qantas will continue to attempt to reach a negotiated outcome with the three unions. Qantas has a meeting with the Transport Workers Union which represents ground staff and baggage handlers on Tuesday, another one with ALAEA on Thursday and with the pilots union on Oct. 28.