NEW DELHI (Reuters) -The head of the world's largest international airline, Dubai's Emirates, voiced frustration on Sunday over chronic aerospace supply problems, challenging planemakers to take responsibility for late suppliers.

Leading plane manufacturers Boeing ( BA ) and Airbus are months and years behind on new plane deliveries, frustrating airlines which want to upgrade to more fuel-efficient aircraft and launch new services.

"I am pretty tired of seeing the hand-wringing about the supply chain: you (manufacturers) are the supply chain," Emirates President Tim Clark said at a news briefing on the sidelines of an airline industry summit.

Emirates has orders for 205 of Boeing's ( BA ) 777X model jets, which have not yet received certification from the U.S. Federal Aviation Administration. Deliveries of the 777X are set to start in 2026, six years behind schedule.

Clark saw a "glimmer of hope" over the certification of new planes, and that Boeing ( BA ) was indicating cautious optimism over its recovery in top-level meetings with the planemaker, he told an annual meeting of the International Air Transport Association (IATA).

Last week, sources told Reuters that Airbus has been warning airlines it faces another three years of delivery delays in working through a backlog of supply-chain problems.

Emirates has not yet seen a shift in demand patterns as a result of U.S. President Donald Trump's recent tariff moves, Clark added.