(Reuters) - United Airlines is close to securing three dozen or more Airbus A321neo jets from aircraft lessors, Bloomberg News reported on Thursday citing people familiar with the matter.

United has been looking for alternatives to Boeing's ( BA ) uncertified MAX 10 planes, which were due for delivery this year and were expected to be the cornerstone of its fleet.

However, a mid-air emergency in January on an Alaska Airlines 737 MAX 9 has raised new doubts over its certification. United had ordered 277 MAX 10 jets with options for another 200.

United had approached Airbus about buying A321neo jets as possible alternatives to its MAX 10 order but the planemaker's order book is full through 2030.

On Tuesday, United CEO Scott Kirby said the airline wants A321 jets but would not be willing to overpay for them.

The airline declined to comment on the Bloomberg report.