The US government has ordered a review of the way Boeing’s 737 Max aircraft got its licence to fly.
It comes after two crashes in five months, amid suggestions from experts that there were “clear similarities” between the disasters.
Transport secretary Elaine Chao has asked the US inspector general to audit the aircraft’s certification process.
One focus of crash investigators has been the Max’s anti-stall system, which Boeing says needs a software update.
In a memo to inspector general Calvin Scovel, Ms Chao said she wanted the review in order to “assist the Federal Aviation Administration [the regulator] in ensuring that its safety procedures are implemented effectively”.
After the crash of the Ethiopian Airlines aircraft last week – which followed a Lion Air disaster in October – there were questions about why the FAA took so long to ground the 737 Max.