Amazon has filed a patent for flying warehouses that could use a fleet of drones to make deliveries to customers.

A document - filed in the US in December 2014 but having only now been unearthed - describes giant airships which could be used to quickly deliver items when demand is high.

Drones (or UAVs) would be dispatched directly from it.

The airships themselves are described as 'airborne fulfillment centres' (AFC).

The patent suggests: "The AFC may be an airship that remains at a high altitude (e.g., 45,000 feet) and UAVs with ordered items may be deployed from the AFC to deliver ordered items to user designated delivery locations. As the UAVs descend, they can navigate horizontally toward a user specified delivery location using little to no power, other than to stabilize the UAV and/or guide the direction of descent.

"Shuttles (smaller airships) may be used to replenish the AFC with inventory, UAVs, supplies, fuel, etc. Likewise, the shuttles may be utilized to transport workers to and from the AFC," it adds.

Such a project is likely years in the future, if it comes to fruition at all. However, Amazon is currently developing and testing a drone delivery service, which it has dubbed 'Prime Air'.