U.S. aircraft maker Boeing has slashed its forecasts for new plane demand due to the industry downturn, and said it was focused on delivering existing orders rather than chasing new ones.

The company said in a report on Thursday it expected 29,000 new planes to be ordered worldwide over the next two decades, down from 29,400 forecast a year ago.

It said the overall value of the new orders would be $3.2 trillion -- the same figure as last year as the price per aircraft is expected to rise.

The forecast cuts reflect the slump in air travel, but also assumes a recovery over the longer term.

Boeing's outlook comes ahead of next week's Paris Air Show, where the Seattle-based firm and European rival Airbus traditionally unveil new plane orders.

The market is difficult today, but we do see it starting to stabilize, Randy Tinseth, Vice President for Marketing at Boeing's commercial planes division, told reporters.

He said air travel was expected to grow by just under 5 percent per year on average over the next two decades, driven by a near 7 percent annual increase in Asia-Pacific.

Tinseth said Boeing was striving to make sure existing orders were delivered and to avoid cancellations, rather than winning new orders.

Any time you go into a downturn it's about getting the backlog in place, rather than acquiring new orders, he said, adding that the current order book was for 3,500 planes.

(Reporting by John Bowker, Editing by Kate Holton and Erica Billingham)