The sightings have also prompted a coastal navigation warning.
It was now "more than likely" the icebergs would end up off mainland New Zealand, National Institute of Water and Atmospheric Research (Niwa) oceanographer Dr Mike Williams said.
The icebergs were spotted by Australian scientists off Macquarie Island last week.
Crew on board fishing vessel Amaltal Explorer reported the icebergs were about 43 nautical miles northwest of the Auckland Islands yesterday morning.
Polar tourist ship Spirit of Enderby also spotted four icebergs 10 miles off the eastern entrance to Carnley Harbour, in the Auckland Islands, expedition leader Rodney Russ said.
"The crew of the vessel has been put on special iceberg lookout as these icebergs pose a significant risk to shipping."
Dr Williams said satellite images from late Wednesday also confirmed a group of about three or four "biggish" icebergs to be in New Zealand subantarctic waters, about 400km-500km from Invercargill.
"They are moving in a northeasterly direction."
Maritime New Zealand yesterday issued a coastal navigation warning for the subantarctic area which would be in force for 48 hours.
It was "more than likely" they would move towards mainland New Zealand.
Mainland Air chief pilot Phil Kean said he had just finished putting the prices on the company's blackboard -$250 per person for chartered flights to the icebergs.
Flights could begin when the icebergs were within 100 nautical miles off the Otago coast, but when those flights would begin was "the burning question", he said.
The company had fielded several inquiries, including one from an Australian television network looking to book a flight on one of its Piper Seneca or Piper Chieftain twin-engined aircraft.
Helicopters Otago managing director and chief pilot Graeme Gale said the company had fielded calls from New Zealand and overseas.
While the icebergs were not yet close enough for sightseeing trips, he anticipated chartered flights would be possible within a week.
Also declaring its interest is Vincent Aviation, of Wellington, which may begin sightseeing flights in the next couple of weeks from the closest airport, possibly Invercargill.
In 2006, when icebergs were last seen off the Otago coast, some made it as far as Stewart Island before some moved east and the others north.
They were travelling about 1kmh-2kmh.
In 2006, it took the icebergs two to three weeks to get close to the mainland.
As the latest icebergs moved further north, they were nearing the end of their lifespan and, as a result, were breaking up.
It was thought the icebergs probably came from the six large icebergs which broke off the Ross Ice Shelf about 2000 - the same collection from which the 2006 icebergs originated.
In 2006, the winter was characterised by strong southerlies, similar to this year, which could be a factor in the icebergs appearing, he said.
Mr Russ said Spirit of Enderby left the Auckland Islands on Wednesday, bound for Macquarie Island, and the crew fully expected to encounter more icebergs.
"We have never had iceberg alerts in the subantarctic islands before.
Iceberg lookouts are a feature of our Antarctic voyages but have not been deemed necessary on a subantarctic expedition, but maybe that will have to change."
Not everyone is excited.
Cruise New Zealand chief executive Craig Harris said icebergs were "the last thing we want in the [New Zealand] waters this summer".
Cruise ships berthed in New Zealand ports during the day, then sailed at night, with vessels "watching out" for any icebergs, he said.
Because of the ships' tight schedules, it was unlikely any of the major vessels would detour for passengers to see the icebergs, he said.
Tourism Dunedin chief executive Hamish Saxton said people were fascinated by icebergs, and "if they come into our backyard, it creates opportunities for us".
