A Boeing 737 Max 9 plane at the Boeing Field in Seattle, Washington on on March 22, 2019.

Boeing documents now under review by a U.S. government committee appear to point to a "very disturbing" picture of commentary from the planemaker's employees over the 737 Max aircraft, a House of Representatives transportation infrastructure committee aide said on Tuesday.

The documents, submitted to the committee late on Monday, discussed concerns over Boeing's commitment to safety, along with efforts by some employees to ensure the company's production plans were not diverted by regulators or others, said the aide, who spoke on condition of anonymity.

Boeing released the following statement:

"Boeing proactively brought these communications to the FAA and Congress as part of our commitment to transparency with our regulators and the oversight committees.

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.

We have made significant changes as a company in the past nine months to enhance our safety processes, organizations, and culture."

The documents were submitted to the Federal Aviation Administration on the same day Boeing announced the firing of its chief executive Dennis Muilenburg amid a crisis following its handling of the aftermath of two fatal crashes involving the best-selling 737 Max.

The 737 Max has been grounded since March. The crashes in Indonesia and Ethiopia killed 346 people within five months.

This latest batch of documents submitted to the FAA contained instant messages from former Boeing senior pilot Mark Forkner, according to a person briefed on the matter.

In October, Boeing turned over 2016 messages to the FAA between Forkner and another pilot that said he might have unintentionally misled the U.S. regulator and raised questions about the performance of a key safety system during testing.

Boeing had earlier turned over the documents to the Justice Department, which has an active criminal investigation underway into matters related to the 737 Max plane.

Boeing is struggling to mend relations with U.S. and international regulators it needs to win over to get the jet back in the air.

Boeing shares, which have dropped more than 20% over the past nine months, closed down 1.3% to $333 on Tuesday.