The carrier’s board of directors made the move on Saturday, due to “unresolved contractual issues” with the aircraft manufacturer, according to Cargolux chief Frank Reimen.

“In the event that the issues cannot be resolved in a timely manner, Cargolux will source alternative capacity to fully meet customer demand and expectations ahead of the traditional high season,” the company said in a press statement issued after its board meeting.

Boeing took a more optimistic line. “We’re continuing to work with Cargolux and look forward to delivering these airplanes,” a company spokesman was quoted as saying in the Seattle Times.

Neither company has revealed the nature of the dispute, however the Boeing spokesman said the first jet “would be ready to deliver on Monday” if not for Cargolux’s decision.

Indeed, Boeing was meant to delivery two of the super jets to Cargolux this week. The carrier was originally set to receive the first plane in 2009, but design problems pushed back the delivery date by two years. Launch customer Cargolux had firm orders for 13 of the freighters and options to purchase 12 more, the company told Delano earlier this year.