(Reuters) -Dubai’s Emirates could cancel an order for Boeing 777X passenger jets if the model’s entry into service slips beyond the end of 2023, the airline’s president was reported saying.

“Honestly, if it goes beyond 2023, and it goes on for another year, we probably cancel the program,” Tim Clark told industry publication AirlineRatings.

“What else can we do? We can’t continue the way we are. Boeing really needs to get their act together and get this aircraft sorted.”

Emirates is the world’s largest international carrier, according to industry data, and largest user of wide-body jets.

“Don’t forget the aircraft was originally designed for delivery in April 2020; it’s now 2024 if we are lucky. You’ve now got a four-year delay with the programme. If they got another year on it, we are going to question if this is fit for purpose or not, what’s the problem with it?”

A Boeing spokesperson said it “remains focused on executing the comprehensive series of tests and conditions to demonstrate the safety and reliability of the airplane’s design”. Boeing will continue to work closely with customers, the company said.

Emirates is the largest customer for the upgraded version of Boeing’s 777 mini-jumbo. The upgrade is facing additional scrutiny and certification delays in the wake of a safety crisis over the 737 MAX.

The plane is due to be certified in mid-2023 but Clark, who has voiced frustration over delays in the past, told AirlineRatings Boeing had only given a conditional response when he had asked whether that certification date remained on track.

He was also reported by AirlineRatings saying Boeing had built 12 of Emirates’ 777X and placed them in storage without their engines.

Emirates originally ordered 150 of the twin-engined jets in 2013, becoming by far their biggest customer. It later trimmed the order to 115 jets partly by swapping them for 787s, and has previously suggested it could switch more of the order to 787s.

However, Clark also criticised a separate issue of production delays of the 787, of which Emirates has 30 on order.

“The total of 30 787s in there look very marginal now as they are so far behind in production,” he was quoted as saying by AirlineRatings.

(Reporting by Alexander Cornwell, Tim Hepher. Editing by Jane Merriman)