WASHINGTON (Reuters) - The National Transportation Safety Board said early Thursday it is sanctioning Boeing for disclosing non-public details of the ongoing investigation into the Jan. 5 Alaska Airlines 737 MAX 9 mid-air emergency.

The NTSB said Boeing had "blatantly violated" the agency's investigative regulations "by providing non-public investigative information to the media and speculating about possible causes of the Jan. 5 door-plug blowout."

The NTSB said Boeing would no longer have access to the investigative information the NTSB produces during its investigation and added the planemaker will not be allowed to ask questions of other participants at an investigative hearing on the door-plug blowout in early August.

(Reporting by David Shepardson; editing by Jason Neely)