Amazon is developing technology that will allow a flock of drones to fly in convoy, allowing the machines to cover longer distances and carry heavier loads.

The company has been granted the patent for a a large and robust flying drone, which is made up of several smaller drones.

The Amazon Technologies Inc. patent says that individual modules could detach from the collective drone body once they were no longer required, allowing them to operate independently to deliver smaller parcels.

The patent description explains that a collective aerial drone would be capable of transporting 'virtually any size, weight, or quantity of items.'

The average drone can typically fly continuously for up to 30 minutes and can only transport items weighing up to 10 pounds.

The company has been granted the patent for a a large and robust flying drone, which is made up of several smaller drones

Last month the company revealed that it had made its first aircraft delivery, of an Amazon Fire TV box and a bag of popcorn

Last month the company revealed that it had made its first aircraft delivery and claimed to have dropped off the package just 13 minutes after it was ordered.

However, investigations later showed that the parcel, containing an Amazon Fire TV box and a bag of popcorn, were flown from Amazon's drone testing site near Cambridge, across one field to a farmhouse just 765 yards away.

Amazon has spent millions of pounds developing its drone service. In July the Civil Aviation Authority (CAA) lifted strict drone flying restrictions to enable the company to start testing its drones.

It means Amazon is allowed to have one pilot controlling multiple autonomous drones and can operate a drone without a direct line of sight.

Over the summer Amazon secretly flew its drones in a field, around five miles east of its research and development centre in Cambridge.

It built a wall of haybales to hide the testing area, but the drone could be spotted when it was flying in the sky.

The secret site also contains a blue control tower, with a five-metre tall antenna, and a manicured landing site, the size of a football pitch to resemble a front garden.

Amazon made its first drone delivery last month, which was launched on a mechanised track at its Prime Air Fullfillment Centre (pictured) before reaching an altitude of 400ft

Amazon plan to roll out the service more widely in the future but said customers would only be able to use the individual drones, pictured, if they lived close enough to a depot and ordered goods that weighed less than 5.7lbs

The area is constantly patrolled by security men and vans, with Amazon keen to keep its latest development to itself.

Amazon has also applied for a patent for anti-collision avoidance systems on their drones.

The company has stated the drones will cruise below 400ft, carrying packages up to 5lbs and guided by GPS.

Amazon does not require a licence for the drones but once it rolls out the service further it will need to obtain the permission of the Civil Aviation Authority for every delivery as all commercial drone flights must be approved by the body.

Questions over the safe use of drones remain, however, with a number of near-misses involving commercial aircraft and amateur drone pilots reported this year.

Amazon has proposed using its crafts in 'segregated blocks of airspace below 500 feet and away from most manned aviation operations'.

The firm also said its drones will use 'sense and avoid' technology and data will be continuously gathered throughout the trial to make improvements, calling safety its 'top priority'.

Amazon Air is launched amid safety concerns - with a number of near-misses involving commercial aircraft and amateur drone pilots reported this year

The firm said its drones will use 'sense and avoid' technology and data will be continuously gathered throughout the trial to make improvements

The company added that the current trial was only permitted to operate during daylight hours with low winds and good visibility, and not in rain, snow or icy conditions.

On its website Amazon said: 'It looks like science fiction, but it's real. One day, seeing Prime Air vehicles will be as normal as seeing mail trucks on the road.'

A spokesman for the CAA said it was 'too early' to talk about granting Amazon exemptions for commercial flights for 'out of line of sight' flights on a national scale.

The spokesman added the company would likely have to get Government approval to pursue such an extension.

Earlier this year Amazon got British approval for three new types of tests, including flying drones that are no longer within sight of their operators in rural and suburban areas.

The other two are having one person operate several highly automated drones and testing devices to make the drones able to identify and avoid obstacles.

Similar technology to Amazon's megadrone has been developed elsewhere, including in Norway.

Students in Norway created a record-breaking remote-controlled multicopter dubbed the Megakopter, which they hope will one day carry people

One potential use for a vehicle of this sort would be to rescue someone trapped on a roof, the team said

A team from the University of Oslo team spent 18 months building a large unmanned aerial vehicle (UAV), dubbed the Megakopter.

It contains 13 propellers and eight hexacopters powered by a total of 48 motors that reside on a frame built from aluminum and plywood.

In October 2015, it broke the world record by lifting a payload of 61kg(134lb 7.6oz) into the air and holding it there for 37 seconds, elevated to a height of at least one meter at all times.