Tension is simmering between U.S. and Ethiopian officials as investigators prepare to release in the coming days an interim report about the Boeing Co. 737 MAX jetliner that nose-dived after takeoff from Addis Ababa on March 10, according to people from both countries.

U.S. investigators, according to people familiar with their thinking, have privately complained that Ethiopian authorities have been slow to provide data retrieved from the black-box recorders of Ethiopian Airlines Flight 302, which went down minutes into a flight to Nairobi, killing all 157 people on board.