BUENOS AIRES (Reuters) - A gigantic iceberg six times the size of Buenos Aires is drifting aimlessly toward Argentina's southern coastline after breaking off Antarctica seven years ago, a high-ranking Navy official said.  ``It is swirling around out there, caught in a very peculiar current, as if in a sort of whirlpool,'' said Hipolito Picasso, meteorology chief at the Navy Hydrographics Service.

The iceberg, labeled ``B10A'', measures 41 miles long and 13 miles wide. It rises up to 60 yards out of the sea and reaches an underwater depth of 300 yards.  The giant block of ice was double its current mass before breaking in two in 1995, said Picasso. It is traveling at a speed of 700 yards per hour and represents a threat to passing ships with the shards that fall from its flanks, he said.

Currently the iceberg is bobbing in the water more than 300 miles off the southeast coast of Tierra del Fuego, Picasso said. The Navy official said in the past five years there have been two icebergs in the southern seas that have been larger than the current floating mass. They broke down and melted, which is what is expected to happen with the current ice bulk, he said.