PARIS -- An iceberg more than twice the size of Luxembourg has ventured into the South Polar seas after wrenching itself free of the Antarctic ice shelf, an expert said.

Two hundred kilometers (120 miles) long, 32 kms (20 miles) wide and about 200 meters (660 feet) thick, C-19 is one of the biggest icebergs seen in recent years, David Vaughan of the British Antarctic Survey (BAS) told AFP.

"The iceberg is still in the Ross sea, about 300 kilometers (200 miles) away from the ice front where it broke off from," he said in an interview from Cambridge, England.

"It won't start melting until it leaves the cold polar waters.

Icebergs can last for years and years and years, absolutely years, as long as they stay in the cold water. "As soon as they get out of the cold water and into warmer and stormy waters they can break up within a few weeks or months."

C-19's formation on the Ross ice shelf was first spotted in May by the U.S. National Ice Center.

Over the next five months, a new European environment satellite, Envisat, monitored its gradual breakout into the open sea, the European Space Agency (ESA) said in a statement.

Envisat's pictures, posted on the esa website (www.esa.int), show C-19 jostling to reach the sea against an older iceberg, B-15A, which is resting aground in shallow water.

B-15A, slightly smaller than C-19, is a fragment of B-15, a vast iceberg which at its peak measured around 11,000 square kilometers (4,400 square miles), making it the size of Jamaica.

B-15 split off from the shelf -- "calved" in scientific terms -- in March 2000 and later broke up into several pieces.

Vaughan said he believed that the emergence of two vast icebergs from the Ross ice shelf in so short a time should not be a cause for worry about global warming.

"Every now and again a big iceberg breaks off the ice shelf and that is absolutely nothing to worry about because they've always done that.

"That's the normal, natural cycle of the ice shelf. There are areas where we've seen ice shelves retreating over the last 50 years, and we think that is a response to climate change, but this is not one of those areas. "The Antarctic peninsula is where climate has been changing most rapidly and where the ice shelves have been retreated. But they don't retreat like this, producing one big iceberg every now and again. They retreat by year-on-year production of lots of little icebergs, a kind of constant retreat." He added: "There's an outside chance that (the calving of C-19) is related to climate change but I want to see a whole set of events like this before I believe that this is the case."

Vaughan said the nearest land to C-19 was New Zealand, several thousand kilometers (miles) away.