PHOENIX • Airbus is seeking airline support for a new 400-seat jetliner provisionally dubbed the A-350-8000 as competition escalates with Boeing over the world's largest two-engined jets, airline and aviation industry sources said.

Two of the airlines whose feedback could be decisive in whether Airbus launches the new jet are Singapore Airlines and British Airways.

After talking up the possibility of a new member of its A-350 family, the European planemaker has swung into an active pre-marketing phase as it responds to a recent upgrade in the competing Boeing 777 series.

While Boeing has scored successes in the Gulf with its biggest twin-engined jet, the 406-seat 777-9, Airbus is expected to aim its design at airlines that do not always require the performance needed for extreme Gulf conditions.

"It would have similar capacity and range (as the 777-9) and substantially lower seat-mile costs," Airbus sales chief John Leahy said in an interview. "We are showing it to airlines right now."

The project is the latest move in a game of leapfrog played by Airbus and Boeing over the past decade in the market for big twinjets, valued at about US$1.9 trillion (S$2.6 trillion) over 20 years.

It marks a shift in priorities after the collapse in oil prices eased pressure on Airbus to upgrade its four- engined A-380, output of which is declining because of slow sales.

Singapore took delivery of its first smaller A-350-900 model this week and has long been weighing up the 777-9, while putting pressure on Airbus to offer it a choice.

Both Singapore Airlines and British Airways declined to comment.

Airbus president and chief executive Fabrice Bregier was visiting Singapore on Thursday for a delivery ceremony, at which a company spokesman declined to comment.

The A-350 XWB (Extra Wide Body) family was launched after a string of setbacks in 2006 to compete with Boeing's mid-sized 787 Dreamliner and the larger 777.

Boeing responded to the all-new jet by upgrading its existing 777 series to include the 777-9. The latter has outsold the A-350-1000 by about 40 per cent, but has entered a lean period since its launch with big Gulf orders in 2014.

Boeing has disclosed 306 sales of 777-9s and a similar variant, while Airbus has sold 181 of its A-350-1000s.

"It is clearly an airplane that is on its own in the marketplace and the airplane is selling very well," Boeing marketing chief Randy Tinseth told the Istat Americas air finance conference, referring to the latest 777 model.

The new, bigger A-350 would use a derivative of the latest Rolls-Royce Trent XWB planned for the A-350-1000. One person briefed on the plans said it would boost thrust from the current 97,000 pounds to about 100,000 pounds.

To give it more capacity and compete with the 777-9 on long trips, engineers are likely to examine design tweaks to boost the maximum take-off weight to a little more than 319 tonnes, compared with 308 tonnes on the Airbus A-350-1000, the person said.

However, it would sacrifice some range compared with the 13,000km A-350-1000.

REUTERS