Qatar Airways, Dubai's Emirates and Kuwaiti lessor Alafco could place hefty aircraft orders at the Dubai Airshow starting on Sunday, industry sources said.

Qatar Airways is expected to place a $6.5-billion order for 50 fuel-saving A320neo jets and five A380s from Airbus, while Emirates is negotiating to place an order for at least 30 and possibly as many as 50 Boeing 777 long-range aircraft worth $8.5 billion to $14.5 billion, the sources said.

The sources stressed that the deals were still being finalised and there was no guarantee they would be completed in time for the show.

They said the final Emirates deal may also depend on the outcome of ongoing financing talks which have been complicated by the decision of several European banks to scale back their exposure to aircraft financing due to the euro zone debt crisis.

Boeing has taken orders for 132 of its 777s this year, and company executives, including the head of its Commercial Airplanes unit Jim Albaugh, have said the airline is on track to set a record number of 777 orders for one year.

Emirates is already a major customer for the 777 and is due to receive the 1,000th aircraft which Boeing began building this week. It has ordered a total of 89 777s since the aircraft was launched in the 1990s and has 41 aircraft on the Boeing order book waiting to be delivered.

The latest model of 777 has a list price of just under $300 million.

The order tally at the airshow is expected to include an enhanced deal by Alafco to buy A320neo aircraft, the sources added.

Airbus, Boeing and the gulf airlines declined to comment, while Alafco's chairman Ahmed al-Zabin reiterated that the company was in talks with Airbus to improve on its order for 30 A320neo planes placed at the Paris airshow earlier this year.

The airshow takes place against a backdrop of economic turmoil in Europe and doubts over global economic growth.

The industry is keen to demonstrate its resilience in the face of these headwinds and a stubbornly high oil price.