Argentina's state airline, Aerolineas Argentinas, plans to order 20 Boeing 737 jets worth $1.8 billion at list price, the companies said in a statement late Monday.

The state flag carrier said the plan to order the 737-800 airplanes is part of its program to update its single-aisle fleet, which already includes 26 737 aircraft.

"This is a landmark order for our company, both in the number of aircraft and in what they signify for our fleet," said Mariano Recalde, president of Aerolineas Argentinas, in the statement.

"This agreement is a key part of a greater plan to renew our fleet and prepare our operations to accommodate growing demand. The Boeing Next-Generation 737-800, which has more seats than our current single-aisle fleet, will give us more flexibility to operate both domestic and regional routes."

Boeing said when the plan is finalized it will be posted as a firm order.

Argentina's president, Cristina Kirchner, nationalized the airline in 2008, when it was nearly $900 million in debt under the ownership of Spanish group Marsans.