Dubai's Emirates is exploring switching some orders for the world's largest jetliner, the Airbus A380, to the smaller A350 in a move raising new doubts about the future of Europe's superjumbo, people familiar with the matter said.

The Gulf carrier, which has invested tens of billions of dollars in more than 100 A380s, has been struggling to finalize a deal to buy another 36 to keep assembly lines open, due to differences with engine maker Rolls-Royce.

Now, Airbus is looking closely at closing A380 factories sooner than expected as part of a reshuffle of orders, with Chief Executive Tom Enders unlikely to leave the situation unresolved when his mandate ends in April, they said.