DUBLIN (Reuters) -Ryanair would look for an alternative aircraft supplier if U.S. tariffs materially affect the price of planes it has ordered from Boeing ( BA ), chief executive Michael O'Leary said in a letter on Thursday, adding that he would consider Chinese planemaker COMAC.

Ryanair, Europe's largest by passenger numbers, is due to take delivery of the final 29 aircraft a 210 plane 737 MAX order by March next year. It also has 150 firm orders for the MAX 10, the largest jet in the 737 family, and options for 150 more, with the first deliveries due in 2027.

"If the US government proceeds with its ill-judged plan to impose tariffs, and if these tariffs materially affect the price of Boeing ( BA ) aircraft exports to Europe, then we would certainly reassess both our current Boeing ( BA ) orders, and the possibility of placing those orders elsewhere," O'Leary said in a letter to a senior U.S. lawmaker seen by Reuters.

O'Leary added that Ryanair would have no need to purchase other aircraft unless tariffs affect the pricing of its Boeing ( BA ) order.

He was responding to a warning by U.S. Representative Raja Krishnamoorthi against Ryanair purchasing Chinese-made aircraft due to security concerns, following prior comments by O'Leary that he would consider doing so at the right price.

O'Leary said in the letter that the Irish airline has not had any discussions with COMAC about aircraft purchases since about 2011 but that it would "of course" consider it if they were 10%-20% cheaper than Boeing's ( BA ) main rival Airbus.