In a secret bunker deep in the Swiss Alps, European researchers have deposited a "digital genome" that will provide the blueprint for future generations to read data stored using defunct technology.

Scientists have carried a time capsule through a labyrinth of tunnels and five security zones to a vault near the slopes of chic ski resort Gstaad.

The sealed box containing the key to unpick defunct digital formats will be locked away for the next quarter of a century behind a 3-1/2 tonne door strong enough to resist nuclear attack, at the data storage facility, known as the Swiss Fort Knox.

"Einstein's notebooks you can take down off the shelf and read them today. Roll forward 50 years and most of Stephen Hawking's notes will likely only be stored digitally and we might not be able to access them all," said the British Library's Adam Farquhar, one of two computer scientists and archivists entrusted with transferring the capsule.

The capsule is the culmination of the four-year "Planets" project, which draws on the expertise of 16 European libraries, archives and research institutions, to preserve the world's digital assets as hardware and software is superseded at a blistering pace.

Around 100 GB of data - equivalent to 24 tonnes of books - has already been created for every single individual on the planet, ranging from holiday snaps to health records, project organizers said, adding this amounted to over one trillion CDs worth of data across the globe.

But as technological breakthroughs help people to live longer, the lifespan of technology gets shorter, meaning the European Union alone loses digital information worth at least three billion euros every year.

The project hopes to preserve "data DNA", the information and tools to access and read historical digital material and prevent digital memory loss into the next century.