A United States panel has asked Boeing Co to make an engineer available for an interview after reports that the worker filed an internal ethics complaint on 737 MAX's safety and that the planemaker convinced the regulator to relax safety standards.

The engineer said in the complaint filed this year that during the development of the 737 MAX, Boeing had rejected a safety system to minimise costs, the New York Times had reported earlier.

The engineer, who worked on cockpit instruments and controls, felt the safety system could have reduced risks that contributed to two fatal crashes that killed 346 people in Ethiopia and Indonesia, according to the report.

“All of this information is critical to have as we prepare for our Committee's October 30th hearing with Boeing's CEO, as well as Boeing's chief engineer of its commercial airplane's division, and the chief pilot for the 737,” said Peter DeFazio, chairman of the US House Transportation and Infrastructure Committee.

Boeing said it would continue to cooperate with Congress and regulatory authorities as it focuses on safely returning the MAX to service.

The committee has been poring over hundreds of thousands of pages of documents and emails from Boeing and the FAA, but it was not aware of the engineer's complaint, he said.

Boeing persuaded the Federal Aviation Administration in 2014 to relax safety standards for the new 737 MAX related to cockpit alerts that would warn pilots of problems during flight, the Seattle Times reported on Wednesday, citing documents.

The regulator struck out four clauses that would be requirements for any new jet being designed today, the report said. That meant the planemaker avoided a complete upgrade of the 737's ageing flight-crew-alerting system, the report added.

Boeing declined to comment on the Seattle Times report.

Boeing's submission cited an estimate that full compliance would cost more than $10 billion, the Seattle Times said.

That amount included the direct cost to Boeing of redesigning the airplane and the expense of additional pilot training, all of which would have been borne by Boeing's airline customers, making the MAX a much less attractive airplane, the report said.

“These reports certainly add to my concern that production pressures may have impacted safety on the 737 MAX, which is exactly why it's so critical we get to the bottom of this,” DeFazio said.

The FAA did not immediately respond to a request for comment.