Europe’s aviation safety agency has imposed strict demands before allowing the grounded Boeing 737 Max to return to service.

The European Aviation Safety Agency (Easa) will run its own tests on the aircraft before approving a return to commercial service.

The 737 Max has been grounded since March after two crashes in Indonesia and Ethiopia killing 346 people.

Easa wants Boeing to do more to improve the integrity of the sensors that failed in the two fatal accidents, the Seattle Times reported.

It is demanding that Boeing demonstrate in flight tests the stability of the Max during extreme manoeuvres, not only with Boeing’s newly updated flight-control system but also with that system switched off.

These were among the disclosures in a presentation to the European Parliament on Tuesday by Easa executive director Patrick Ky.

Ky listed what appeared to be more stringent requirements than its US counterpart, the Federal Aviation Administration (FAA).

Boeing is hoping for FAA clearance for the Max in October so that it can return to passenger service in the US this year.

FAA approval would apply only to US carriers flying domestically. European airlines flying the Max, such as Norwegian Air and Tui Airways, require clearance from Easa.

Easa told the newspaper: “We can confirm that Easa is not yet satisfied with the proposed solution by Boeing on the improved architecture and logics for the AOA (Angle of Attack) system.

“We are following a methodical approach to assess the overall safety of the flight control and associated functions of the aircraft, as well as the pilot interaction with the systems, to take account of the human factors involved.”

The FAA said: “The FAA has a transparent and collaborative relationship with other civil aviation authorities as we continue our review of changes to software on the Boeing 737 Max.

“Our first priority is safety, and we have set no timeframe for when the work will be completed.

“Each government will make its own decision to return the aircraft to service based on a thorough safety assessment.”

Iata director general and CEO Alexandre de Juniac told Reuters in Chicago that “with the 737 Max we are a bit worried … because we don’t see the normal unanimity among international regulators that should be the case.”

“We see a discrepancy that’s detrimental to the industry,” de Juniac added, urging regulators to make any changes to the single certification process “collectively”.