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A "doomsday" seed vault built to protect millions of food crops from climate change, wars and natural disasters opened Tuesday deep within an Arctic mountain in the remote Norwegian archipelago of Svalbard.

"The Svalbard Global Seed Vault is our insurance policy," Norway's Prime Minister Jens Stoltenberg told delegates at the opening ceremony. "It is the Noah's Ark for securing biological diversity for future generations."

European Commission President Jose Manuel Barroso and 2004 Nobel Peace Prize winner Wangari Maathai of Kenya were among the dozens of guests who had bundled up for the ceremony inside the vault, about 425 feet deep inside a frozen mountain.

"This is a frozen Garden of Eden," Barroso said.

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The vault will serve as a backup for hundreds of other seed banks worldwide. It has the capacity to store 4.5 million seed samples from around the world and shield them from man-made and natural disasters.

Dug into the permafrost of the mountain, it has been built to withstand an earthquake or a nuclear strike.

Norway owns the vault in Svalbard, a frigid archipelago about 620 miles from the North Pole. It paid $9.1 million for construction, which took less than a year.

Other countries can deposit seeds without charge and reserve the right to withdraw them upon need.

• Click here for the official Web page of the Svalbard Global Seed Vault (in English).

The operation is funded by the Global Crop Diversity Trust, which was founded by the U.N. Food and Agriculture Organization and Biodiversity International, a Rome-based research group.

"Crop diversity will soon prove to be our most potent and indispensable resource for addressing climate change, water and energy supply constraints, and for meeting the food needs of a growing population," said Cary Fowler, head of the Global Crop Diversity Trust.

Svalbard is cold, but giant air-conditioning units have chilled the vault further to -0.4 degrees Fahrenheit, a temperature at which experts say many seeds could last for 1,000 years.

Stoltenberg and Maathai delivered the first box of seeds to the vault during the opening ceremony — a container of rice seeds from 104 countries.

"This is unique. This is very visionary. It is a precaution for the future," Maathai, a Crop Diversity Trust board member, told The Associated Press after the ceremony.

The seeds are packed in silvery foil containers — as many as 500 in each sample — and placed on blue and orange metal shelves inside three 32-foot-by-88-foot storage chambers.

Each vault can hold 1.5 million sample packages of all types of crop seeds, from carrots to wheat.

Construction leader Magnus Bredeli-Tveiten said the vault is designed to withstand earthquakes — successfully tested by a 6.2-magnitude temblor off Svalbard last week — and even a direct nuclear strike.

Many other seed banks are in less protected areas. For example, war wiped out seed banks in Iraq and Afghanistan, and one in the Philippines was flooded in the wake of a typhoon in 2006.

"So much of the value of Svalbard is that it is so far away from the dangers," Fowler told The Associated Press during a tour of the vault on Monday.

From the outside, only the entryway is visible. It resembles an elongated concrete tower capped by a glass artwork depicting frozen ice crystals.

Ahead of the opening, the entrance was decorated with igloo-like cubes of snow and an ice sculpture of a polar bear.

Seed vault worker Jimmy Olsen was standing outside with a rifle slung from his shoulder.

"My job is to keep away people who aren't supposed to be here, and guard against polar bears," he said.

There are an estimated 3,000 polar bears on the islands.

A long, steel-lined tunnel leads to three separate chambers for storing seeds, each reached through a frost-covered metal door.

Reactions from around the world have been mostly positive, but the world spotlight brought by the seed bank has met a cool reception from some locals who treasure the isolation of the Arctic archipelago.

"We like to be here a little bit for ourselves," said Kai Tredal, 42, one of the roughly 2,000 residents of Svalbard's main town of Longyearbyen.

The crop trust, which is helping Norway manage the project, said it was seeking deposits from the world's biggest seed banks first.

Fowler added that even if power systems failed, the permafrost around the vault would help keep the seeds "cold for 200 years even in the worst-case climate scenario."

He expected the vault's life span to rival that of Egypt's ancient pyramids.