A new batch of messages between Boeing employees on the development of the 737 Max paints a "very disturbing picture" of concerns about the plane, according to an aide to a US House committee.

The documents were turned over to the Federal Aviation Administration on Monday, the agency said in a statement. The disclosure came the same day that Boeing ousted its chief executive officer.

At least some of them were written by the same Boeing pilot whose 2016 messages were released in October and were the subject of sharp questioning by lawmakers, according to a person familiar with their contents who wasn't authorised to discuss them.

The communications haven't been released publicly. The staff of the Transportation and Infrastructure Committee are still reviewing the messages and didn't provide specific details about what they contain.

"The committee will continue to review these and other records provided by Boeing as part of the committee's ongoing investigation,"

"But similar to other records previously disclosed by Boeing, the records appear to point to a very disturbing picture of both concerns expressed by Boeing employees about the company's commitment to safety and efforts by some employees to ensure Boeing's production plans were not diverted by regulators or others," a committee aide said in a statement.

"The committee will continue to review these and other records provided by Boeing as part of the committee's ongoing investigation," the aide said.

Boeing brought the emails to the FAA and Congress "as part of our commitment to transparency with our regulators and the oversight committees," the company said in a statement.

"As with prior documents referenced by the committee, the tone and content of some of these communications does not reflect the company we are and need to be," the company said. Boeing has made changes to enhance safety, it said.

Boeing fell 1.3 per cent to US$333 at the close in New York, as markets shut down early because of Christmas Eve.

This was the second time that the Chicago-based company has delayed turning over to the FAA sensitive messages related to the development of the 737 Max. The jetliner was grounded in March after a design flaw was linked to two fatal crashes, in Indonesia and Ethiopia. The earlier episode involving messages prompted a rebuke by the agency and stirred tensions between the regulator and the planemaker.

The new incident adds to the challenges awaiting David Calhoun, the Boeing chairman who is poised to become CEO next month following the ouster on Monday of Dennis Muilenburg. A statement from the board cited deteriorating relations with the FAA as part of the rationale for the move.

Boeing's handling of the second set of records rankled the agency, according to a person familiar with the issue who wasn't authorised to speak about it. Boeing told the FAA the messages existed in recent days, but didn't initially provide them or disclose their contents, said the person.

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The FAA didn't comment in its statement on the content of the emails, saying only that they were under review. The company's decision to turn the emails over to the FAA was reported earlier by the Seattle Times.

In October, Boeing disclosed to the FAA instant messages and emails by a high-ranking company pilot who in 2016 expressed misgivings about the software implicated in two fatal crashes on the Max.

Boeing had known about those messages since early in the year and turned them over to the Justice Department in February. It didn't give them to the FAA immediately because of the criminal investigation into how the plane was approved, Bloomberg News reported at the time.

The delay angered the FAA, which is charged with overseeing Boeing. One of the agency's key tenets is that entities it oversees must disclose safety issues or possible breaches of regulations. In some circumstances, failing to tell the agency about such an issue may be considered a legal violation.

"The FAA finds the substance of the document concerning," the agency said in a statement on October 18. "The FAA is also disappointed that Boeing did not bring this document to our attention immediately upon its discovery."

The November 2016 instant messages disclosed in October, which were reviewed by Bloomberg News, were between between Mark Forkner, then Boeing's chief technical pilot for the 737, and another 737 technical pilot, Patrik Gustavsson.

Forkner expressed concern that the flight-control feature later implicated in the crashes was "running rampant" and said he might have unknowingly misled the FAA about it. In separate emails he sent to an unnamed FAA official, he said he was "Jedi-mind tricking" regulators outside the US into accepting Boeing's suggested training for the Max.

A lawyer for Forkner, David Gerger, said issues raised in the messages were the result of balky simulator software and not a result of problems with the plane itself. Forkner believed the plane was safe and didn't mislead the FAA, Gerger said.

Gerger didn't respond to requests to comment on the latest messages and whether they involved his client.