Activists who have led the fight against Japan's whaling operations in the Southern Ocean say reports of the annual whale hunt being suspended are a bluff.
Regular attempts by the Sea Shepherd Conservation Society to interrupt hunts have caused irritation in Japan.
"Putting safety as a priority, the fleet has halted scientific whaling for now," said Tatsuya Nakaoku, an official at the Fisheries Agency.
"We find Sea Shepherd's harassment extremely regrettable."
But Sea Shepherd captain Paul Watson said he was suspicious about the true movements of the Japanese.
Whaling boat the Nishin Maru was in the Drake Passage between South America and Antarctica and could be returning to the Southern Ocean via the Indian Ocean, he told Radio New Zealand.
"I believe that they might be trying to head across the South Atlantic and into the Indian Ocean to come on the other side of their whaling grounds to start again and then they'll send their harpoon vessels west."
If that was the case the society would have the protest ships Bob Barker and Steve Irwin box them in at their arrival.
He said if it was necessary, the protest vessels would follow the whalers right around the world.
Meanwhile the Government reacted cautiously last night to the reports of the whaling suspension.
"The Government has had no official confirmation of these reports but will be seeking clarification from the Japanese government," a spokeswoman for Foreign Minister Murray McCully told NZPA.
Green Party MP Gareth Hughes said Japan's whaling season seemed to have ended.
"There is a chance this could be the last whaling season in the Southern Ocean and New Zealand needs to keep up the pressure," Mr Hughes said.
"This has been a terrible season for the Japanese whalers, who have had to cut it short and who have only caught between 30 to 100 minkes, far short of their quota of up to 935 minkes and 50 fin whales."
Japan's Jiji Press Agency reported the Government was considering calling the fleet home earlier than the usual end of the hunt, which would be in mid-March.