Low-cost Qantas offshoot Jetstar International will today launch long-haul overseas fares it believes are up to 30 per cent lower than the cheapest everyday fares available from competitors.

The airline will also unveil even lower sale fares to get people travelling to the six international destinations that will initially be serviced by its fleet of four ex-Qantas Airbus A330-200 jets.

"We'll have an extremely competitive offering on these routes and destinations," Jetstar spokesman Simon Westaway said yesterday.

"Some of them are obviously becoming a very high demand for Australians travelling abroad and our standard, lead-in fares, we believe, will be up to 30 per cent below anything that has previously been in the market in terms of lead-in, day-to-day fares.

"Obviously, we think we'll bring some competitive tension to these markets but we really believe we'll have the lowest cost base of any international airline operating (in) Australia."

Jetstar International hopes to be flying by November and is part of a push to promote the Qantas Group as two brands. The strategy will see Qantas mainline aircraft flying higher-yield routes frequented by business travellers, and Jetstar taking on thinner long-haul leisure routes.

Jetstar International will initially fly from Sydney to Honolulu, Bali, Phuket, Ho Chi Minh City and Osaka; from Melbourne to Honolulu, Bali and Bangkok; and from Brisbane to Osaka. It will fly up to six, 303-seat A330-200 jets with two classes, "StarClass" and economy.

The StarClass seats will be similar to Qantas domestic business class and will include in-seat power, frequent flyer points, meals and beverages and video on demand.

The airline has Qantas board approval to expand to 12 widebody aircraft by 2009-10 and will be the launch vehicle for Qantas's new fleet of more efficient Boeing 787 "Dreamliners".

Mr Westaway said the Jetstar and Qantas operations would be complementary where possible and that the airline was already analysing where it would fly to next.

He said it would ultimately look at flying from Australian cities other than Sydney, Brisbane and Melbourne, but this might not be until the 787s arrived.

"Clearly, there will be growth in our long-haul routes," he said.

"To put that in perspective, inside three years Jetstar's international business will actually be greater in size and in terms of total operations than the domestic and trans-Tasman business operated by our narrow-body fleet.

"And we predict that with the introduction of the 12 787s over the next four years, the Jetstar International business will create an airline that is 10 times its existing size," he said.

The airline has yet to get regulatory approval for its proposed launch and needs permission to fly its twin-engine planes up to 180 minutes away from emergency airports.

Qantas pilots, who are worried Jetstar will be used as a weapon to erode their pay and conditions - Jetstar pilots are paid up to $100,000 a year less - have urged the Civil Aviation Safety Authority not to grant the 180-minute approval, for safety reasons.