An iceberg has been spotted from the New Zealand shore for the first time in 75 years, one of about 100 that have been drifting south of the country.

The giant ice chunk was visible Thursday from Dunedin on South Island but has since moved away, driven by winds and ocean currents.

The flotilla of icebergs — some as big as houses — were first spotted south of New Zealand early this month.

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Last year, icebergs were seen in the country's waters for the first time in 56 years. But the last time one was visible from the New Zealand shore was June 1931, said Mike Williams, an oceanographer at the National Institute of Water & Atmospheric Research.

Scientists have been reluctant to blame global warming.

"We've been monitoring these things for such a short time, it's impossible to see. To say this is unusual and related to global warming is just not possible," Paul Augustinus, an Auckland University glacial geomorphology lecturer, told the New Zealand Herald earlier this month.

"It's a fairly frequent occurrence; it's just unusual for such large bergs to get so far north," he added.

Williams has said winds from a series of southern storms probably had driven some of the icebergs close to South Island. He said they were surviving longer than expected and taking a different route than expected.

Scientists were trying to pinpoint where the icebergs broke off from the Antarctic ice shelf.

Williams said a sample was taken from one of the iceberg when a helicopter landed on it several days ago and was sent for analysis to Victoria University in Wellington.

Maritime New Zealand spokesman Steve Corbett said the icebergs were not being actively monitored because "they pose no imminent danger to shipping."

The icebergs have become a tourist attraction, with sightseers paying more than $300 each to fly over them.

Graeme Gale, the managing director of a company that flies tourists over the icebergs, said they were impressive no matter how many times he sees them.

"It won't last forever, but it's pretty unique," he said.