Etihad Airways may be on the brink of cancelling or deferring orders for Boeing's 777X jets, estimated to be worth billions of dollars, a report said.

The order is for 25 777X jets, the largest and most efficient twin-engine carrier, said a report in bizjournals.

The Abu Dhabi-based airline is reviewing its fleet plan and may be willing to incur penalties for cancellations rather than take all 25 jets, the report added.

Etihad is a launch customer of the 777X: an upgrade to Boeing’s successful mini-jumbo series that includes plans for the world’s largest twin-engined jetliner - the 406-seat 777-9 - which is due to enter service in 2020.