Foreign Minister Murray McCully says the people caught fishing illegally from two foreign vessels in the Southern Ocean are well-known repeat offenders.
The offshore patrol vessel HMNZS Wellington spotted one of the ships about a week ago and has been collecting photographic and video footage.
It is thought the ships are fishing for toothfish.
Foreign Minister Murray McCully said the two vessels are claimed to be registered in Equatorial Guinea in Central Africa.
New Zealand was seeking permission from that country to board the ships.
Mr McCully said they had asked Interpol to put out alerts and were working with nearby ports to ensure the vessels could not offload their catch.
"This is a really shabby activity plundering what's a delicate resource down there. These guys are really serious crooks and we're going to throw the book at them in every way we possibly can," he said.
"We'll make sure they're not able to land their catch at any reputable port and we'll continue to make representations to any parties that seem to have connections to the vessels."
New Zealand has also alerted the Spanish Government, as the ships' owners have previously been linked to Spanish interests.