Shares in Airbus parent EADS cruised to their highest level in nearly four years on Wednesday, boosted by hopes of a potentially record airplane order set to be announced by American Airlines.

Sources told Reuters the board of parent AMR was voting overnight on an aircraft order worth tens of billions of dollars for several hundred aircraft, expected to be split between Boeing and Airbus.

The airline is expected to unveil the order for Boeing 737 and Airbus A320neo-family jets at around 1100 GMT on Wednesday.

American Airlines last ordered Airbus planes in the late 1980s and declared in 1996 Boeing would be its exclusive airplane provider through 2018. If Airbus wins all or even part of a big order from the carrier, it would be a coup.

We're talking about a massive order, and EADS will probably get a big chunk of it. EADS's stock has risen a lot lately, but they still have a pretty strong momentum, a Paris trader said.

In late morning trading, EADS shares were up 2.5 percent at 24.56 euros after rising as much as 4.3 percent in brisk volume.

The deal is also expected to provide a boost to General Electric and France's Safran which look poised to sweep up a broad deal for the engines, industry sources said. Shares in GE partner Safran rose 3.6 percent to 28.71 euros in Paris.

Estimates for the overall size of the deal have ratcheted steadily upwards with several sources talking of a deal for about 400 planes to be shared between Airbus and Boeing and one source familiar with the deal talking of a very large number.

Airbus landed a record single-manufacturer order for 200 planes at the Paris Air Show last month, sparking a race from airlines anxious to save fuel by buying revamped efficient jets.

French brokerage Cheuvreux said the latest deal could trigger a slew of purchases by Delta , United Continental Holdings , Southwest and US Airways .

The board vote follows tense haggling that saw Boeing agree to match Airbus and update its best-selling 737 medium-haul jet with new engines to offer fuel savings, industry sources said. That marks a retreat from ambitious plans for a full redesign.

AMR, Boeing and Airbus declined to comment on the talks.

The market for narrowbody jet sales is estimated at $2 trillion over 20 years and is split between Boeing and Airbus, whose A320 has made substantial U.S. inroads.

The European company said last year it would put a more fuel-efficient engine in its A320 family and call it A320neo. The A320neo aircraft is scheduled to enter service in late 2015.

Airbus dominated the Paris Air Show last month with orders for the A320neo, putting pressure on Boeing to respond, and the contest for American's business has brought the battle over strategy between the world's leading planemakers to a head.

Boeing has debated whether to redesign its 737, a workhorse for airlines around the world, or put a new engine in it.

Experts say re-engining should deliver fuel savings of 15 percent. Up to 25 percent could be achieved by an all-new plane but it would cost five times more to build, or $10 billion.

In a crucial modification, industry sources said Boeing had drawn up another option which would call for a smaller engine than one planned for the Airbus neo, offering about 3-5 percent less fuel savings but avoiding the cost of the full neo revamp.

Boeing's plane is lower to the ground than Airbus's meaning the U.S. company would need to raise the undercarriage and modify parts of the wing to squeeze in the type of GE/Safran engine which is being offered to Airbus. This latest option would preserve the shape of the world's most-sold aircraft.

(Additional reporting by Kyle Peterson, Karen Jacobs)