* Emirates order for up to 36 A380s blocked by dispute
* Airbus seeks deal to switch some to A350 - sources
* Airbus studies closing A380 line but no decision yet (Adds analyst comment, details)
By Tim Hepher and Alexander Cornwell
PARIS/DUBAI, Jan 31 (Reuters) - 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 iconic 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 finalise 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.
A person familiar with the matter said Airbus was looking "extremely seriously" at setting the timetable for a shutdown but said no decision had been taken.
Airbus said in a statement after Reuters first published news of the talks that it "confirms it is in discussions with Emirates airline in relation to its A380 contract". But it said details of negotiations were confidential.
Emirates and Rolls-Royce declined to comment.
The A380s have been used to promote a luxury lifestyle with the Emirates brand, featuring lounges and showers on board, and were part of the set for a 2017 advertisement with Hollywood actor Jennifer Aniston. It says the jets, some with over 600 seats, have helped the airline at slot-constrained airports.
But sales of such four-engined planes are tumbling as many airlines switch to smaller and less thirsty twin-engined jets like the A350 and Boeing 777 due to improving size and range.
Emirates announced the lifeline order for up to 36 superjumbos worth as much as $16 billion at list prices a year ago, throwing a lifeline to the programme's roughly 3,000 workers and securing its future for at least another decade.
But a year-long impasse between Emirates and Rolls-Royce over shortfalls in fuel savings has so far blocked the order.
Airbus is trying to broker a complex workaround which could see Emirates take smaller jets also powered by Rolls-Royce while it tries to secure homes for as many A380s as possible, with British Airways recently expressing interest.
Airbus has dangled the prospect of closing A380 production before, and industry sources say such manoeuvres can be a negotiating tactic and the talks remain difficult to predict.
But time is running out for the A380 with few airlines willing to spend the sums invested by Emirates, which has made it a backbone of its global network alongside the Boeing 777.
The production line is "untenable", a senior industry source said. Jefferies analyst Sandy Morris said closing production could release capacity for painting and other future production.
If confirmed, a decision by Emirates to order the A350 would ease a separate headache for Airbus and engine partner Rolls-Royce after Emirates axed an A350 order in 2014.
Airbus and Rolls are keen to maintain a foothold at the largest Arab carrier and prevent Boeing filling the gap with more of its General Electric-powered 777s. The A350 competes with both the Boeing 777 and smaller 787.
Any deal depends on the backing of Emirates which sources say holds many of the cards in the sometimes heated discussions.
Rolls continues to owe the Dubai carrier penalties for underperformance on Trent 900 engines already in its A380 fleet, giving Emirates leverage to win a good deal on A350 engine maintenance.
Also likely to weigh a game plan, analysts said, is Boeing . It blocked an earlier Airbus bid to put the A350 back in Emirates with a draft deal for 40 787s in 2017, and is seen likely to renew the effort as it negotiates to close the deal. (Reporting by Tim Hepher and Alexander Cornwell Editing by Edmund Blair amd Phil Berlowitz)