Boeing is being sanctioned by U.S. investigators for sharing information about a federal investigation of a door plug blowout that left a gaping hole in a Boeing 737 Max 9.

The National Transportation Safety Board said Thursday that Boeing “blatantly violated” the agency's investigative regulations as well as a signed agreement by providing non-public investigative information to the media and speculating about possible causes of the Jan. 5 door plug blowout on a Boeing passenger jet in Portland, Oregon.

During the incident, a panel that plugged a space left for an extra emergency door blew off an Alaska Airlines Max 9. Pilots were able to land safely, and there were no injuries.

The NTSB said that on Tuesday during a media briefing, a Boeing executive provided non-public investigative information to the media about the Alaska Airlines incident that the agency had not verified or authorized for release. The NTSB said that Boeing portrayed the NTSB's investigation as a search to find the individual responsible for the door plug work, but the agency said it's focused on the probable cause of the accident, not placing blame on any individual or assessing liability.

Boeing did not immediately respond to a request for comment early Thursday. Shares of The Boeing Co., based in Arlington, Virginia, were flat before the opening bell.

“Because of Boeing’s recent actions, Boeing will retain its party status, but no longer have access to the investigative information the NTSB produces as it develops the factual record of the accident,” the agency said in a prepared statement.

The NTSB said that it may subpoena any relevant records it requires during the course of the investigation. It also will subpoena Boeing to appear at an investigative hearing in Washington D.C. on Aug. 6 and 7. The agency said that, unlike other parties, Boeing won't be able to ask questions of other participants.

The NTSB said that it will coordinate with the Department of Justice's Fraud Division, giving them information about Boeing’s recent unauthorized investigative information releases related to the 737 Max 9 door plug investigation.

In May the Justice Department told a federal judge that Boeing had violated a settlement that allowed the company to avoid criminal prosecution after two deadly crashes involving its 737 Max aircraft.

It is now up to the Justice Department to decide whether to file charges against Boeing. Prosecutors will tell the court no later than July 7 how they plan to proceed, the department said at the time.