(Reuters) - Air China Ltd, the country's flag carrier, said Monday it signed an agreement to order 60 Boeing B737 planes for a total price of $5.9 billion.

The aircraft are to be delivered between 2016 and 2020 per the agreement, which was disclosed Monday in an Air China regulatory filing.

The order comes four months after Boeing Co won an order for 80 737 planes from Singapore-based BOC Aviation.

Boeing said in September it expects China to need more than 6,020 aircraft in the next 20 years, an 8 percent rise over last year's two-decade estimate, as growing overseas leisure travel drives demand.

That same month Boeing delivered the first of seven 747-8 Intercontinental jumbo jets to Air China, which was one of the few carriers to order the fuel efficient aircraft.