Boeing Co. will step up pressure on archrival Airbus on Tuesday with a $2.8 billion deal for its biggest cargo plane expected from airline Emirates, which recently walked away from plans to buy the freighter version of the Airbus A380 superjumbo.

Industry sources said the deal would be announced at the Farnborough International Airshow under way near London.

Officials at Emirates and Boeing declined to comment.

Airbus and Boeing wage a fierce battle to outdo the other in orders announced at the biennial event, though this year France-based Airbus is struggling, its reputation hurt by costly delays of the A380 and its indecision over plans to build a new mid-sized model.

Boeing launched its new, larger 747-8 version of the venerable 747 jumbo last November and has named two buyers so far, with a third unidentified buyer booked for the passenger version, dubbed the 747-8 Intercontinental.

Airbus has 3 customers signed up for its A380F (freighter) and a total of 16 buyers for both versions of the plane, which is due to enter service with Singapore Airlines late this year.

The 747-8 is due in 2009.

In overall annual orders, Airbus has beaten Boeing for five consecutive years but in 2006 Boeing has pulled far ahead.

Airbus at the air show on Monday laid out plans for a new mid-sized model dubbed the A350 XLB for extra wide body which it hopes to formally launch in three months' time with an eye to deliveries beginning in 2012.

The $10 billion redesign underscores the high stakes involved in its battle with Boeing.

(Reporting by Tim Hepher, Jason Neely and Bill Rigby)