The delay was because of General Electric Co <GE.N> engines not meeting performance guarantees, said Qatar Airways CEO Akbar Al Baker at an unrelated event at Boeing's plant in Everett, Washington, north of Seattle, rather than any issue with Boeing.

"There was a shortfall of nearly 2.7 percent," in the engines' fuel burn, said Al Baker, whose Qatar Airways recently took a 35 percent stake in Cargolux, and who has taken a close interest in the freight company's business. "We couldn't take an aircraft that is underperforming."

He declined to comment on whether Cargolux would receive compensation from GE for the engines not meeting agreed standards.

Al Baker, known for his vocal criticism of Boeing and rival Airbus <EAD.PA>, said postponement of the 747-8 freighter delivery was not related to negotiations over compensation for Qatar's delayed order for smaller Boeing 787s.

"It is absolutely unrelated. I cannot use Cargolux to get additional concessions from Boeing (for Qatar Airways)," said Al Baker. "There is no relationship between 787 delays and the Cargolux aircraft."

Al Baker said he expected to receive the first of Qatar Airways' 787s in the middle of next year, later than his last projection of February, due to extra time the airline wants to fit its own equipment in the planes, which he claimed would make Qatar's 787s the "most luxurious" in the skies.

Boeing declined comment on when the first 747-8 freighter -- the latest and biggest version of its storied jumbo -- would be delivered to Cargolux.

The delivery was scheduled to take place 11 days ago, but had to be scrapped at the last minute when Luxembourg-based Cargolux refused to accept delivery, without explanation.

(Reporting by Bill Rigby. Editing by Robert MacMillan and Gunna Dickson)