Australia's Qantas Airways' fleet worldwide remained grounded for a second day Sunday, stranding tens of thousands of passengers across the globe.

Qantas officials and unions representing workers, as well as government and business leaders have appeared before a labor tribunal, but have not yet reached a resolution to the labor dispute.

Australian Prime Minister Julia Gillard said Saturday she had asked for the country's industrial regulator to intervene and end a series of ongoing strikes. She said she made the move because the escalating dispute could have major economic implications.

Qantas Chief Executive Alan Joyce abruptly grounded all Qantas aircraft Saturday because of the strikes, announcing all striking employees would be locked out beginning Monday evening.

The airline is seeking to end a prolonged battle with its unions over pay, working conditions and plans to set up new airlines in Asia.

The unions represent pilots, licensed engineers, baggage and ground workers, and catering staff.

The company says the grounding of the fleet will cost Qantas more then $20 million a day. The airline says strikes have already cost the company $16 million a week. It said the total financial impact so far has been almost $70 million.