A draft interim report from Ethiopian crash investigators circulated to US government agencies concludes the March 2019 crash of a Boeing 737 MAX was caused by the plane's design, two people briefed on the matter have said.

Unlike most interim reports, this one includes a probable cause determination, conclusions and recommendations, which are typically not made until a final report is issued.

The US National Transportation Safety Board has been given a chance to lodge concerns or propose changes, those briefed said, declining to be identified because the report is not yet public.

NTSB spokesman Eric Weiss confirmed the agency had received the draft interim report, but declined to comment on whether the agency would suggest any changes.

Boeing declined to comment to Reuters about the report.

According to Bloomberg News, which first reported the contents of the interim draft, the conclusions say little or nothing about the performance of Ethiopian Airlines or its flight crew and that has raised concern with some participants in the investigation.

The Ethiopian interim report contrasts with a final report into the Lion Air crash released last October by Indonesia which faulted Boeing's design of cockpit software on the 737 MAX but also cited errors by the airline's workers and crew.

Ethiopian Airlines flight 302 crashed in an open field six minutes after take-off from Addis Ababa, the Ethiopian capital, killing 157 passengers and crew.