June 28 (Reuters) - Alaska Airlines said on

Friday it has returned to Boeing ( BA ) the 737 MAX 9 plane that

in January was involved in a mid-air door panel blowout.

"They have taken possession of it and the registration has

been changed," an Alaska Airlines spokesperson said, adding an

order for a new 737-10 has also been placed.

Boeing ( BA ) has

informed its suppliers there will be a delay in a key

production milestone for its 737 jet family by three months,

sources told Reuters' earlier this month.

U.S. investigators on Thursday

sanctioned

Boeing ( BA ) for revealing details of a probe into the blowout

and said they would refer its conduct to the Justice Department,

prompting the planemaker to issue an apology.