A source at THAI said three of the aircraft were operating on the Bangkok-New York route and that the other one would be delivered by next month.

The source did not disclose the price details of selling the four aircraft but said it would be about the same as buying new ones.

"THAI's executive board members are expected to make a final decision about the sale today," said the source.

The purchase of the A340-500s was made by former THAI chairman Thanong Bidaya as part of a five-year plan to expand the airline's long-haul routes, including New York.

THAI has been operating the Bangkok-New York route since 2005.  However, the route has been operating on a very low load factor, due to poor demand.

The source estimated the airline had already lost up to Bt5 billion from the New York route.

The airline is considering suspending the route for a period of months. But some executives believe operating a long-haul service would help the airline increase revenues, as well as its passenger base.

Wallop Bhukkanasut, executive vice president of the airline's Commercial Department, said THAI was likely to suspend the Bangkok-New York route soon.

He said the company was also considering choosing new aircraft to replace the A340-500s.

"I have recommended using the Boeing 777-200, which could operate long-haul routes. At the moment, THAI has no such aircraft, so there are plans to use the Boeing 777-200, which consumes less energy than the A340-500, " said Wallop.

The airline has projected total revenues of Bt160 billion this fiscal year (October 2006 to September 2007). During the first five months of the accounting year ending in February, THAI's revenues increased 14 to 16 per cent year on year.

The airline expected to increase its cabin factor from 76 per cent last year to 79 to 80 per cent this year.

The airline has also adjusted downwards the fuel surcharge on some highly competitive routes, such as Bangkok-Sydney and Bangkok-Frankfurt, in order to attract more travellers.

Meanwhile, it is also planning to revise fares on low-competition routes like Bangkok-Bangalore, to entice passengers.