The confirmation of an order for 66 planes, plus an additional order for around 30 A330neo jets is expected to be announced by AirAsia CEO Tony Fernandes later on Thursday, people familiar with the matter said.

AirAsia is not expected to place additional single-aisle Airbus jet order as it expands A330neo order, sources said.

The company was discussing the possible purchase of another 100 Airbus A321neo jets as Fernandes and Airbus went down to the wire in parallel negotiations for an expanded order for larger A330neo jets, industry sources said on Sunday.

The airline said it would hold a media event on Thursday in Kuala Lumpur at 5:30 p.m. local time (0930 GMT) for a major announcement related to developing long-haul operations, which are operated by its AirAsia X Bhd arm.

AirAsia X has a firm order for 66 of the fuel-efficient A330neo widebody jets to replace its older first-generation A330s but it has been pushing back the delivery dates. It is Airbus' biggest customer for the A330neo and the widebodies will help meet its ambition of returning to the Kuala Lumpur-London route it dropped in 2012 due to low demand and high fuel prices.

The airline also has a firm order for 10 A350s placed in 2009, but Fernandes in April said that jet was "too expensive" and would not be purchased.

AirAsia has been a steadfast Airbus narrow-body and wide-body customer, but recently the company has talked to Boeing Co about buying the rival 787 jet as an alternative, a person familiar with the discussions told Reuters in April.

The announcement comes two days after Fernandes said AirAsia had not yet taken a decision on which aircraft maker to pick.

(Reporting by Tim Hepher in Farnborough and Liz Lee and Anshuman Daga in Kuala Lumpur; Writing by Jamie Freed Editing by Christian Schmollinger and Gopakumar Warrier)

By Tim Hepher and Liz Lee