The project, dubbed the Noah’s Ark for seeds, will catalogue and preserve more than threemillion species to ensure the long-term survival of the world’s vital food crops.

The vault — on an island on the Svalbard archipelago, 620 miles (1,000 km) from the North Pole — will be carved into the side of a mountain where the temperature is unlikely to rise above -3C (27F), even in the event of severe global warming. It will be surrounded by concrete walls 1m (3ft) thick.

The precious contents will be accessed by a single door using one of six master keys held by international bodies such as the United Nations. Nature, in the form of blizzards, ice floes and marauding polar bears, will provide security.

Over the next decade the 50m-long (164ft) vault will be filled with foil-packed samples of every crop variety. These will be held in “black boxes” and will be released only if all other seed sources have been destroyed or exhausted.

As political leaders from five Nordic countries laid the cornerstone of the vault, the project’s designers said that it would provide a “fail-safe” means of protecting global agriculture against catastrophe. “This facility will provide a means to re-establish crops obliterated by major disasters,” said Cary Fowler, of the Global Crop Diversity Trust, which drew up the feasibility plans.

“But crop diversity is imperilled not just by a cataclysmic event, such as a nuclear war, but also by natural disasters, accidents, mismanagement and short-sighted budget cuts.”

The project was spearheaded by the Norwegian Government, which is providing the initial funding of £2 million, and the trust, an international non-profit organisation that works to support the most critical crop collections, which are held in about 1,400 gene banks around the world. The trust will pay the operational costs.

Dr Fowler said that recent conflicts in Rwanda, Iraq and Afghanistan had all resulted in the eradication of seed samples.

Jens Stoltenberg, the Norwegian Prime Minister, said: “This seed bank is of global importance. It will be the only one of its kind. It is our final safety net.”

He said that it would provide back-up not only against disasters, but also if a commercial gene bank is destroyed. He said that this had already happened 40 times.

The feasibility study concluded that, under proper conditions, seeds for most main food crops could remain viable for hundreds of years at the Arctic site. Others, including key grains, could survive for thousands of years.

Scientists estimate that there are two million species of plant used in agriculture, with a further million wild variants. This includes about 100,000 types of rice, the main staple of human diet, and more than 1,000 varieties of banana.

By the end of the 19th century there were more than 7,000 named varieties of apple grown in the United States. There are now only 200.

The Government’s Foresight programme recently identified important food crops grown in sub-Saharan Africa that are likely to be affected by global warming.

Geoff Hawtin, a British plant geneticist and founder of the Global Crop Diversity Trust, told The Times that it was likely that the facility would be accessed once or twice a year.

He said that the two million samples would be in place within nine years, and that, in the event of a global catastrophe, the vault would not feed the world but offer the survivors a future. “This will give us the opportunity to rescue the foundation of agriculture built up over the past 10,000 years,” he said.

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