Boeing on Thursday forecast a $4 trillion market for 33,500 passenger jets over the next 20 years.

The forecast, which covers sales by Boeing and Airbus and other smaller aircraft manufacturers, signals a strong increase in demand on the eve of the Paris airshow which starts on Monday.

The world market has recovered and is now expanding at a significant rate, said Randy Tinseth, vice president of marketing at Boeing's commercial division.

(Reporting by Tim Hepher)