Wellington, Sept 16 NZPA - Qantas-owned budget airline Jetstar today detailed a signalled expansion in the New Zealand domestic market, which it says will keep Air New Zealand honest.

Jetstar said it would fly 39 extra weekly services between Auckland, Christchurch, Wellington and Queenstown from February 2011, expanding its current offering by 50 percent and taking a near 20 percent share of the domestic New Zealand market.

Jetstar Group chief executive Bruce Buchanan and newly appointed Australia-New Zealand chief executive David Hall said the expansion amounted to 717,000 additional annual domestic seats.

The airline started flying domestically in 2005 and its expansion comes as Pacific Blue exits the New Zealand market in October.

Mr Buchanan declined to say if Jetstar was profitable on its domestic routes, though the airline said it turned a profit in the New Zealand market in July last year.

Jetstar carried more than a million passengers domestically in New Zealand in the year to June 30, according to the latest Qantas result.

Jetstar is one of the fastest growing airlines in the region, servicing 17 countries, with a fleet of 65 aircraft and 350 flights per day, according to Qantas.

Mr Buchanan told NZPA the airline was making sure "we have got something that can keep Air New Zealand honest".

Qantas used to lose a considerable amount of money on domestic New Zealand services.

Jetstar's 20 percent share of the market was a much more viable second carrier position, he said.

The company also launched a sale and a self-service initiative today.

The company is investing $100 million in the New Zealand market and is creating 100 jobs, 50 in Christchurch and 50 in Auckland as a result of the expansion.

The Christchurch earthquake on September 4 had not changed the Jetstar's confidence in the New Zealand market, but it cost the company "in the low millions of dollars" in lost bookings and the half-day closure of Christchurch airport.

"We haven't seen any impact in bookings beyond September," he said.

The expansion also comes after the Australian competition regulator the Australian Competition and Consumer Commission blocked, in an preliminary opinion, a plan by Air New Zealand to work with Virgin Blue Holdings Ltd on trans-Tasman routes.

After Pacific Blue signalled its departure Air New Zealand said it would boost domestic capacity.

Christchurch International Airport Chief Executive Jim Boult said the Jetstar expansion would help replace the flights lost from Pacific Blue's withdrawal, and provide an extra boost for the tourism industry.

"In light of the earthquake, it's wonderful to get good news like this, which supports the ongoing growth of tourism in our region. We invite people to come visit the region -- there's great snow at the local ski-fields and key attractions in Canterbury are open," he said.

He said 99 percent of all tourism operators in Christchurch were now fully functional and they were preparing for an influx of visitors during the upcoming school holidays.