Doomsday vault begins deep freeze

Engineers have begun the two-month process of cooling down a "doomsday vault", which will house seeds from all known varieties of key food crops.

The temperature inside the Svalbard Global Seed Vault will drop to -18C (0F) in order to preserve the seeds.

Built deep inside a mountain, it aims to safeguard the world's crops from future disasters, such as nuclear wars, asteroids or dangerous climate change.

The first seeds are scheduled to arrive at the Arctic site in mid-February.

The Norwegian government is paying the $9m (£4.5m) construction costs of the vault, which will have enough space to house 4.5 million seed samples.