European budget airline Ryanair says it is buying 175 Boeing 737-800 aircraft, the biggest-ever order of Boeings by a European airline, The Associated Press reported.

Boeing confirmed the sale agreement Tuesday, March 19.

Neither side disclosed the purchase price, but Ryanair said it negotiated a hefty discount off the aircraft's total list price of $15.6 billion. Industry analysts said Ryanair most likely has agreed to pay less than $8 billion.

Ryanair already operates a fleet of 305 Boeing 737-800 aircraft. Ryanair chief executive Michael O'Leary says the Dublin-based airline says it plans to replace some older aircraft but take its fleet over 400 by 2019, when it expects to be carrying more than 100 million passengers annually.

Ryanair said O'Leary and Boeing chief executive Ray Conner signed the agreement Tuesday in New York.