Google is buying Titan Aerospace, a solar-powered drone company.

The purchase – for an undisclosed sum – is part of the internet giant’s strategy of delivering access to the web to remote parts of the world.

Titan is developing drones as big as a commercial airliner, which fly at a height of almost 20,000 metres (65,000 feet) and can stay up for as long as five years without ever having to land and refuel. They can then be landed and reused.

Google has already experimented with balloons designed to beam internet access to underdeveloped parts of the world.

Last August New Mexico-based Titan unveiled its Solara 50 and 60 unmanned aircraft. Powered by the sun they have a mission range of more than four million kilometres.

The drones, which are are known as atmospheric satellites, can conduct many of the operations performed by an orbital satellite but are much cheaper and more versatile.

“Atmospheric satellites could help bring internet access to millions of people, and help solve other problems, including disaster relief and environmental damage like deforestation,” Google said.

Facebook had also reportedly been interested in buying Titan for $60 million.

Facebook is working on its own fleet of drones, satellites and lasers to bring internet connectivity to underdeveloped parts of the globe where web access is not yet widely available.