OSLO Norway's navy set sail this week for the Barents Sea to track down the missing plane used by legendary polar explorer Roald Amundsen, who disappeared 81 years ago, hoping to resolve an Arctic enigma.

Over some 10 days, two vessels will scour 36 square nautical miles (120 square kilometres) of seabed close to the island of Bjoernoeya in a bid to locate the remains of Amundsen's seaplane.

“We are about to embark on a bold initiative which provides the only opportunity to solve one of Norway's most enduring mysteries what happened to Roald Amundsen and his men?” expedition leader Rob McCallum of New Zealand wrote on his blog on Monday.

The first explorer to navigate the Northwest Passage that connects the Atlantic and Pacific Oceans in 1903-1906 and the first to reach the North Pole in 1911 after an epic duel with Englishman Robert Scott, Amundsen is, together with Fridtjof Nansen, Norway's biggest name in polar exploration.

In 1926, he flew over the North Pole in an airship, the Norge, with Italian explorer Umberto Nobile and American adventurer Lincoln Ellsworth.

Despite tensions that ensued with Nobile, Amundsen two years later offered to fly to rescue him and his crew, who had flown to the pole again on the airship Italia but crash-landed on the sea ice on the way back.

For the unprecedented international rescue effort, the French government made available to Amundsen a twin-engine Latham 47 - at the time an ultra-modern aircraft.

On June 18, 1928 around 4pm, Amundsen, Norwegian pilot Leif Dietrichson and four French nationals took off from the northern Norwegian town of Tromsoe.

Between 6.45 and 6.55 pm, the crew sent a radio message, then nothing more the seaplane and its crew disappeared, probably off Bjoernoeya, the

southernmost part of the cluster of islands that make up the Svalbard archipelago.

The circumstances of their disappearance have never been established and their bodies have never been found. Nobile and most of his crew survived.

The Norwegian navy vessel KNM Tyr, equipped with two underwater robots, will now search the seabed northwest of Bjoernoeya, supported by a ship from the Norwegian coastguard, the KNM Harstad, to find the seaplane's engines.

“We are concentrating on the engine because as the plane was made of wood, we think it would have rotted away,” Vegard Hatten, a Norwegian navy spokesman, told AFP.

“If it really is in the presumed area, we will find it with our sophisticated equipment,” he added.

The expedition hopes that its potential finds will shed some light on the circumstances of Amundsen's disappearance did the seaplane crash into the water? Or did the crew manage to land in the sea in the middle of a storm only to succumb to the polar waters?

Since the day of the disappearance, only a pontoon and a fuel tank from the Latham 47 have been recovered.

The fuel tank has since been kept in a museum in Tromsoe and its condition lends credence to the theory that the plane had to make an emergency sea landing.

“Someone used a knife and a large hammer on the tank. This proves that someone survived but they were not properly equipped to survive in water. They probably tried to get back to the ice cap,” Kjell Lutnes, a member of the search party, told the NTB news agency.

In 1933, a fisherman hooked an object that may have been a piece of the Latham's wreckage, according to experts, but his line broke, leaving the enigma intact.—AFP