Airbus on Monday raised its 20-year demand forecast for airliners, as many airlines modernize their long-haul fleets and booming Asian economies turn to air transport.

In its annual report on trends in the aviation industry, the world's largest aircraft manufacturer forecasts that the global fleet will more than double over the next two decades to 48,230 aircraft.

Airbus expects to deliver 42,430 new aircraft over the next 20 years, including 41,490 airliners, both figures up 4% on the previous survey.

Airbus divides its demand forecasts between trips generally made on single-aisle aircraft, the industry's best-selling models, and the marathon segment for wide-body aircraft.

Airbus raised its forecast for total demand for wide-body aircraft by 9% to 8,920 units, thanks to double-digit increases in South America and North America. The Group reduced its forecast for the Middle East by 2% amid reports of overcapacity.

Demand for single-aisle passenger aircraft such as the Airbus A320 and Boeing 737 series, which have a short to medium range, was revised up by 3% to 33,510 units.

The manufacturer's forecasts are based on economic expectations that 1.7 billion people will join the middle class and have the income to travel by air over the next 20 years.

"We expect particularly strong growth in Asia and the Middle East, especially India and China," said Bob Lange, Head of Market Analysis and Forecasting at Airbus. "China's domestic traffic will overtake that of the US," he added.

The data published in the Airbus report highlights the boom in traffic in India, with the subcontinent served by the three fastest-growing flows in the world.

(Reported by Tim Hepher, edited by Augustin Turpin)