AIRSHOW-UPDATE 1-Ethiopian to buy Airbus A350 jets

* Order kickstarts Dubai show but business seen down

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DUBAI, Nov 14 (Reuters) - Ethiopian Airlines will firm up an order for around 12 A350 jetliners worth almost $3 billion at the Dubai Air Show, industry sources said on Saturday.

The order is expected to bring sales of the future mid-sized, long-range passenger jet above the 500 mark.

EADS (EAD.PA) subsidiary Airbus has so far sold 493 of the planes, which are due to be available from the middle of next decade to compete with Boeing's 787 Dreamliner. The Boeing model has posted sales of 840 aircraft.

The biennial air show runs from Nov. 15-18, with orders expected to be down sharply due to the recession.

Airbus declined to comment.

In July, the planemaker said Ethiopian Airlines had signed a provisional deal to buy 12 Airbus A350-900 planes.

If confirmed such a deal would be worth $2.9 billion at list prices. (Reporting by Tim Hepher, John Irish; Editing by Raissa Kasolowsky)