The world's biggest iceberg has begun moving nearly three months after it stopped its slow float toward colliding with a huge Antarctic ice tongue (search), New Zealand officials said Monday.

Known as B15A (search), the giant iceberg, a remnant of a Ross Ice Shelf (search) fracture in 2000, is now moving slowly northward out of McMurdo Sound, where it had been blocking sea access, Antarctica New Zealand chief executive Lou Sanson said.

He said the iceberg is moving just over a half-mile a day.

Earlier, B15A, which is 1,200 square miles and contains enough water to feed the River Nile for 80 years, was expected to smash into the ice tongue, possibly cracking it apart.

"We know very little about what makes this thing tick. Every time someone has made a prediction about it, they've been proved wrong," Sanson said.

B15A has blocked wind and water currents that break up ice floes in McMurdo Sound during the Antarctic summer, causing a build-up of ice behind it. The U.S. McMurdo Station and New Zealand's Scott Base are located on the sound, while Italy's Terra Nova base is nearby.

The iceberg and the ice buildup have been in the path of ships supplying fuel and food for the three stations.

The ice blockage has also threatened penguin breeding colonies, with tens of thousands of Adele penguin chicks facing starvation as parent birds are forced to trudge up to 110 miles to open sea to gather food.

Sanson said the "pleasant surprise" had been that the movement of the iceberg had cleared a narrow channel through the sea ice for about 20 miles toward the pier at McMurdo Station.

"It still hasn't cleared (out of the area) but it's moving in the right direction," he said.