PARIS: Aviation giant Boeing has raised its forecast for global aircraft demand, saying it expected 36,770 planes to be delivered over the next two decades in deals worth $5.2 trillion (3.8 trillion euros).

The forecast is up 4.2 percent from Boeing's projection last year, with about a third of the total demand to come from the Asia-Pacific region.

The maker of the best-selling 737 jetliner said rising demand for single-aisle planes from low-cost carriers is expected to drive growth.

Boeing forecast global sales of 25,680 new airplanes in this sector, making up some 70 percent of predicted sales.

"Based on the overwhelming amount of orders and deliveries, we see the heart of the single-aisle market in the 160-seat range," said Randy Tinseth, vice president for marketing at Boeing Commercial Airplanes.

"There's no question the market is converging to this size, where network flexibility and cost efficiency meet."

The higher forecast comes amid concerns about the outlook for the aviation sector after Air France-KLM and Lufthansa both cut their earnings targets due to weak demand.