DUBAI, June 3 (Reuters) - Saudi budget airline flyadeal

is studying a possible order for between 10 and 20 wide-body

jets to carry more passengers, and could make a decision by the

end of the year.

The low-cost subsidiary of state carrier Saudia is in the

early stages of comparing the Boeing 787 and Airbus A330neo, CEO

Steven Greenway told Reuters. It has not yet started a formal

competition between planemakers, he added.

Such a deal would be worth up to around $5 billion at list

prices, though airlines typically win sharp discounts.

Saudia Group, owner of Saudia, and flyadeal placed an order

for a total of 105 Airbus narrow-body aircraft last month.

Among larger aircraft, Jeddah-based Saudia already operates

the Boeing 787 and the A330ceo, an earlier version of the

A330neo which is an upgrade based on new engines.

"We have on our back doorstep an operator, in our owner,

that has intimate knowledge of both aircraft, which is very

helpful to us," Greenway said in an interview.

The larger A350, the latest Airbus wide-body jet which

competes with both the Boeing 787 and 777, is less likely to be

a contender because it was built for longer ranges than flyadeal

needs, Greenway said.

"The A350s are a great airplane, but they're over-engineered

for what we need," he told Reuters on the sidelines of the IATA

airline association's annual meeting in Dubai.

Greenway, a former senior executive at Singapore Airlines

subsidiary Scoot, which operates Boeing 787s, was

appointed CEO of flyadeal in January.

Saudi Arabia's aviation sector is expanding as the kingdom

invests billions of dollars in its Vision 2030 plan to diversify

its economy away from fossil fuels and boost its private sector.

"We have mapped out a long term plan (in which) we could

potentially have a fleet of 10, 15, 20 - I would say 10 minimum

in the next three, four or five years," Greenway said, referring

to the airline's study of wide-body aircraft.

Such planes - which designers say can seat up to around 400

passengers in all-economy configurations - could be attractive

for the number of seats amid slot constraints in places like

Dubai, though they could also open new routes, Greenway said.

"If we can't get any more slots ... then the only choice

you've got beyond the (Airbus) A320 is getting a wide-body to

operate the service," Greenway said.

The Airbus narrow-body jets purchased by flyadeal in its

recent order can seat up to 240 people.

Greenway dismissed concerns that budget airlines have a poor

track record of operating large aircraft, saying the Atlantic

market had unique competitive pressures while large planes were

more routinely used to fly relatively short distances in Asia.