Airbus struck back at rival Boeing in the battle for plane orders at the Farnborough airshow on Tuesday, revealing a surprise multi-billion-dollar firm deal for the future A350. US planemaker Boeing announced larger orders in terms of value for its future 737 MAX aircraft but stressed that they were only commitments at this stage. Boeing had upstaged its main European competitor on Monday -- the opening day of the Farnborough airshow near London -- with a massive firm order for its MAX jets. Airbus on Tuesday said that Hong Kong airline Cathay Pacific had made a firm order for 10 of its long-haul A350 planes worth $3.2 billion (2.6 billion euros). Cathay also agreed to convert 16 of its existing orders for the A350-900 to the larger A350-1000, earning Airbus another $1.0 billion before the possibility of discounts which are often the case with large purchases. The deal was a major boost for Airbus, a day after it revealed only a tame order for four of its future single-aisle neo passenger planes -- a rival to Boeing's MAX series -- to Arkia Israel Airlines for a combined $453 million. Also on Monday, Airbus chief executive Fabrice Bregier conceded that there could be new delays to the delivery of its A350 plane which is due to enter service in mid-2014. Reacting Tuesday to the Cathay deal, Bregier said: "This announcement from one of the world's most highly respected airlines is a clear endorsement of the unbeatable operating economics offered by the A350-1000. "The A350-1000 will be a game changer in the 350-seat category, offering outstanding payload-range capability and a 25 percent reduction in fuel burn." The A350 is a response to Boeing's 787 Dreamliner, which is now flying after long technical delays. The real battle though at the week-long Farnborough show -- a key biennial event in the aviation sector calendar -- is for orders of short-haul aircraft. Boeing is seeking to steal a march over France-based Airbus, which has enjoyed great success in the upgraded single-aisle sector with more than 1,400 firm orders for its A320neo. Boeing's has 549 firm orders for the MAX. Boeing on Tuesday unveiled a commitment to sell 100 upgraded single-aisle 737 planes worth a combined $9.2 billion to US leasing group GECAS. Though still to be finalised, the deal builds on Boeing's announcement Monday of a firm order worth $7.2 billion for 75 of its short-haul 737 MAX jets with US group Air Lease Corporation. The US company on Tuesday revealed a commitment by GE Capital Aviation Services (GECAS), the commercial aircraft leasing and financing arm of General Electric, to purchase 75 737 MAX 8s and 25 Next-Generation 737-800s. "Boeing looks forward to working with GECAS to finalise the details of the agreement, at which time the airplanes will be posted to the Boeing Orders & Deliveries website as a firm order," it said. Boeing on Tuesday also announced that Kuwaiti aircraft leasing company ALAFCO had committed to buy 20 of its 737 MAX planes worth a combined $1.9 billion -- the first such commitment from a Middle Eastern company for the new model. "This is the first commitment for the 737 MAX from the Middle East which is one of the aviation industry's highest growth regions," said Ray Conner, president of Boeing's commercial airplanes division. Boeing's 737 MAX is an upgraded and more fuel-efficient version of the 737, the world's best-selling commercial airplane. The first 737 MAX is scheduled to be delivered in 2017, two years after the neo, which has been billed as a more fuel-efficient A320 thanks to engine upgrades. The 737-800 is meanwhile already in service. Elsewhere on Tuesday, Canadian aircraft manufacturer Bombardier said it had signed a letter of intent with Latvia's airBaltic for up to 20 of its future CSeries planes looking to compete with the neo and MAX. Bombardier said the airBaltic deal for its CS300 planes, which are due to enter service in late 2013, could be worth up to US$1.57 billion.