Japan vowed to continue its whale hunt in the Southern Ocean after clashes with the militant conservationist Sea Shepherd group, which claimed Tokyo had been forced to end the mission.
"We are keeping our whaling programme," an official at Japan's Fisheries Agency told AFP on Thursday, denying a report that Japan was forced to suspend its whale hunt after collisions with boats crewed by anti-whaling campaigners.
The official also repeated Tokyo's claim that the conservationists had rammed Japanese whaling ship the Nisshin Maru on Wednesday, their worst confrontation in the Southern Ocean in three years.
On Wednesday, the anti-whaling group -- which earlier this month lost a battle at the US Supreme Court over an order to steer clear of Japan's whaling fleet -- accused the Japanese side of deliberately colliding with its vessels.
Sea Shepherd captain Paul Watson told the Australian Associated Press news agency that the whalers were refuelling at sea in an area where such activities are prohibited by an Antarctic treaty.
"I feel that this is the end of it," he was quoted as saying, pointing to the 18 days remaining in the short whaling season and deriding the Japanese fleet's moves as "like a case of road rage".
A spokesman for Japan's Institute of Cetacean Research said Thursday that the ship could not be refuelled "due to Sea Shepherd's dangerous activities".
Sea Shepherd is chasing the Japanese fleet hunting whales off Antarctica, as it has done for years in a bid to harass the whalers and prevent the mammals being slaughtered.
Australian Environment Minister Tony Burke has described Japan's whale hunt as cruel and unnecessary but has so far rejected calls to send an Australian government vessel to monitor the hunt.
Japan claims it conducts vital scientific research using a loophole in an international ban on whaling agreed at the International Whaling Commission (IWC), but makes no secret of the fact that the mammals ultimately end up on dinner plates.
Japan defends whaling as a tradition and accuses Western critics of disrespecting its culture. Norway and Iceland are the only nations that hunt whales in open defiance of a 1986 IWC moratorium on commercial whaling.
Sea Shepherd founder Watson is wanted by Interpol after skipping bail last July in Germany, where he was arrested on Costa Rican charges relating to a high-seas confrontation over shark finning in 2002.
Canadian Watson stepped down from key roles last month, passing the Antarctic harpoon chase mantle to former Australian politician Bob Brown.
Watson's whereabouts had been a mystery until December, when he confirmed that he was back on board a Sea Shepherd vessel and ready for the group's annual Southern Ocean expedition against the Japanese whaling fleet.
Anti-whaling Australia launched legal action challenging the basis of Japan's so-called "scientific" hunt in December 2010.
The court will now set the case down for a hearing in The Hague with Canberra anticipating it will be listed for the latter half of 2013.