As Amazon remains at loggerheads with the Federal Aviation Administration (FAA) over its Prime Air drone delivery service, the online retail giant has taken its operations north of the border to develop its technology with greater regulatory freedom. A report in The Guardian on Monday revealed that the company has been testing its drones for the last few months at a top secret site in British Columbia, Canada.

Since Amazon first revealed its Prime Air project in 2013, a service that would see packages under 5 lb (11 lb) dropped at the doors of customers within 30 minutes, progress has been slow. While the FAA has handed out exemptions to companies looking to use drones as part of their business operations, it wasn't until this month that the FAA finally granted the company an "experimental airworthiness certificate," enabling it to put its drones to the test.

The problem was, however, that the approval only pertained to a certain model of drone. A drone that Amazon says had since been improved upon and had become obsolete. In response, Amazon's vice president of Global Public Policy Paul Misener revealed that the snail-like progress of the agency had compelled the company to begin testing more advanced models abroad. But where exactly this had been taking place, and just how close to US airspace, was not known until now.

Just 2,000 ft (610 m) from the US border, Amazon has bought a chunk of land to carry out testing of its drones with the full consent of the Canadian government. Watched over by teams of security guards, the company's roboticists and engineers, which The Guardian says includes a former NASA astronaut and the designer of the wingtip of the Boeing 737, are refining the obstacle avoidance and safety capabilities of the drones. This includes how they perform in different weather conditions and how they might be controlled if there is a breakdown in connection.

Also revealed is that Amazon has set its sights on a certain chunk of airspace, higher than 200 ft (61 m) where most buildings end and beneath 500 ft (152 m), where general aviation starts. The company envisions autonomous drones weighing less that 55 lb (25 kg) zipping through dedicated 10 mi (16 km) long corridors at 50 mph (80.5 km/h) with small parcels in tow.