A Japanese whaling vessel has been forced to return to Japan mid-way through the southern whaling season, Greenpeace claims.
The environmental lobby group says the damaged harpooning vessel Yushin Maru II left the Indonesian port of Surabaya on Saturday morning after seeking repairs several days ago.
A spokesperson for Greenpeace in New Zealand, Karli Thomas, says Indonesian authorities have said the vessel is returning to Japan, rather than rejoining the whaling fleet in the Southern Ocean.
"We don't know why that is - they've certainly got some damage to their ship. But if they do return to Japan, that's going to cut the hunt potential of the fleet quite significantly, because this is one of only three harpoon boats in the fleet."
Japan's whaling programme says it will not comment on the status of its vessels.
The Steve Irwin returns to Hobart
Meanwhile, the ABC reports the anti-whaling ship Steve Irwin has returned to Hobart in Tasmania.
The Steve Irwin met the Japanese whaling fleet in the Southern Ocean in late December, and spent two weeks chasing the ships.
But in early January it ran low on fuel, forcing it to return to Australia.
Captain Paul Watson says there is now nothing stopping the Japanese from hunting whales.
"It will probably be anything between five to seven whales a day, but what we're ensuring is they won't make any profit," he said.
The Steve Irwin will leave Hobart on Wednesday, and plans to pursue the whaling fleet until March.