Air China announced a deal to buy four airliners from Boeing on Friday, citing a list price of 1.15 billion dollars but saying it received "significant price concessions" on the transaction.

The flag-carrier did not name the actual price it would pay for the planes, but said it enjoyed a similar discount in another deal with Boeing last month.

In a statement to the Hong Kong stock exchange, Air China said it expected to take delivery of the Boeing 777-300 planes between mid-2013 and mid-2014.

The airline said the new planes would increase its fleet capacity by four percent and improve services for travellers.

"The transaction would optimise the fleet structure of the Company and is in line with the market requirements for the Company," the Air China statement said.

"The Company expects the Boeing aircraft will deliver more cost-efficient performance and provide more comfortable services to passengers."

In June Air China announced a deal to buy 20 short-to-medium range Boeing 737-800s, with a list price of 1.4 billion dollars, to meet growing demand.

Boeing opened an aircraft maintenance hanger at Shanghai's Pudong Airport last October and in the same month predicted China's aviation market would produce orders for 3,710 new commercial aircraft over the next 20 years.