Pacific Blue's announcement of new trans-Tasman services is seen as part of a plan by parent company Virgin Blue to create an Asia-Pacific network.
Yesterday Pacific Blue said it would start flying nine return trips a week from Auckland to Sydney, starting in October.
The airline said it would be getting another 180-seat Boeing 737-800 aircraft in early September to fly the new route, bringing its total fleet number to nine. The new services added nearly 169,000 extra seats each year.
A fortnight ago the company announced it would fly between Auckland and Melbourne from next month.
Virgin's operations were to stretch beyond Australasia and the Polynesian islands - including Fiji, Samoa and the Cook Islands - to the United States, the Sydney Morning Herald reported today.
In December, its international offshoot, V Australia, begins 10 return flights a week on the trans-Pacific route.
Virgin Blue confirmed yesterday it was on track for its first scheduled flight between Sydney and Los Angeles on December 15.
A Shaw Stockbroking analyst, Brent Mitchell, said: "They struggle to make money in New Zealand but they see it as part of a long-term plan to be able to link in with the US services."
Deutsche Bank analyst Cameron McDonald said the ability of carriers to maintain passenger numbers on the trans-Tasman route would be helped by the strength of the Australian dollar against the kiwi.
A slowdown in the economies on both sides of the Tasman might not be altogether negative for airlines because Australian travellers could favour New Zealand over jetting to Europe or the US, he said.
"(Virgin) are trying to manage the capacity as best they can, so they clearly think the market is there to take delivery of that (extra Boeing) aircraft," he said.