* 17.5 hour flight to Auckland delayed to February from December

* Airbus says its 2016 A350 delivery targets unchanged  

Qatar Airways has delayed the launch of the world's longest scheduled direct flight - from Doha to Auckland, New Zealand - by two months because of the late delivery of Airbus A350s, an airline spokeswoman said on Tuesday.

"I can confirm we are looking at February. It's due to aircraft availability, specifically the delay in delivery of A350s," the spokeswoman said.

The 17.5 hour, 9,031-mile service on Qatar Airways' Boeing 777 fleet to New Zealand had been due to start on December 3 this year.

Qatar Airways increased pressure on Airbus over aircraft reliability last month, saying it had some "issues" with the A350 passenger jet barely a year after it entered service.

An Airbus spokesman declined comment on individual airline delivery schedules, but said its overall target of at least 50 A350 deliveries in 2016 remained unchanged.

Qatar Airways is the largest customer of the A350, a mid-sized carbon-composite jetliner designed to compete with the Boeing 787 Dreamliner and the larger Boeing 777.

It has so far taken delivery of eight of the jets.

Qatar Airways said on Sunday it would reduce the frequency of several routes from Doha including a newly-announced weekly flight to Adelaide in Australia, because of hold-ups in the delivery of new planes from Airbus.

About half a dozen A350 aircraft were seen by Reuters parked and waiting for delivery at their Toulouse assembly site last month, two of which may have since been delivered. These did not include jets painted in Qatar colours, but it was not possible to see inside the assembly hall or hangars.

Qatar's national carrier is also one of the airlines affected by delays in deliveries of smaller A320neo jets, at least three of which are stranded in Qatar Airways livery at Airbus factories while waiting for their engines.

Delivery delays come at a time when both manufacturers and airlines are under pressure from tight supply chains and concerns over demand after years of growth, giving some carriers an incentive to use any gaps to adjust to economic weakness.

While putting heat on manufacturers over delays, Qatar Airways has said its premium traffic yields have slipped in the face of weaker business sentiment and a drop in spending by oil producers.

But the fast-growing Gulf carrier insists it wants the aircraft it has ordered and has threatened to use Boeing to meet part of the shortfall.