Hong Kong ( CNN ) -- Environmental activists and Japanese whaling authorities have reported fresh clashes in Antarctic waters , with each side accusing the other of causing dangerous collisions between ships . The conflicting claims follow harsh words and threats of legal action exchanged between the two sides last week amid activists ' attempts to impede the Japanese vessels ' annual hunt for whales in the Southern Ocean . The Institute of Cetacean Research ( ICR ) -- which conducts whaling activities under the authority of the Japanese Ministry of Agriculture , Forestry and Fisheries -- accused ships from the environmental group Sea Shepherd of `` sabotage . '' During an attempt by the whaling fleet 's main ship , the Nisshin Maru , to refuel on Monday , Sea Shepherd vessels `` repeatedly forced their way '' between the Japanese ship and the fuel tanker , ramming into them in the process , the ICR said . It released short videos showing collisions between vessels . Competing accounts . But Sea Shepherd 's Australian division countered with a different version of events , saying that the Nisshin Maru had caused the collisions . The group said that a Sea Shepherd ship , the Bob Barker , became `` sandwiched '' between the Nisshin Maru and the fuel tanker after positioning itself to block the refueling . `` In the turbulence of the combined wake , the Bob Barker was slammed back and forth between the Nisshin Maru and the fuel tanker , '' Sea Shepherd said . It also claimed the Nisshin Maru rammed another Sea Shepherd vessel , the Sam Simon , `` causing hull damage along most of the port side of the ship and smashing their satellite communications dome . '' No injuries were reported in the clashes , but the Nisshin Maru `` decided to interrupt her refueling procedure due to the extremely dangerous and foolhardy behavior '' of the Sea Shepherd vessels , the ICR said . Crews are still determining to what extent the Nisshin Maru and the refueling ship were damaged , it said . The two sides also traded accusations about the use of water cannon and ropes that snarl up ships ' propellers . Sea Shepherd says the fuel tanker 's presence in the area is illegal , but the ICR says it is `` essential for the safe navigation '' of its ships , which are carrying out a `` perfectly legal activity . '' Legal threats . The Australian government last week called the Japanese activities in the Southern Ocean `` unacceptable '' and vowed to press on with an international legal action to stop the annual whale hunt . Those comments came after reported clashes in which Sea Shepherd vessels blocked a previous refueling attempt . Sea Shepherd said the Japanese ships had intruded into Australian territorial waters and breached international and Australian law . But the ICR says a U.S. court has banned Sea Shepherd from threatening whaling ships ' operations or sailing within 500 yards them . It said it will provide `` additional evidence '' to the court about the latest incident . Prime Minister John Key of New Zealand on Tuesday called for `` cool heads '' to prevail in the tense situation in the Southern Ocean , local broadcaster TVNZ reported . Japan annually hunts whales despite a worldwide moratorium , utilizing a loophole in the law that allows for killing the mammals for scientific research . Whale meat is commonly available for consumption in Japan . Each year , environmental groups such as Sea Shepherd face off with Japan 's hunters in a high seas drama that has led to collisions of ships , the detaining of activists and smoke bombs fired back and forth between the groups . CNN 's Yoko Wakatsuki in Tokyo , and Neda Farshbaf in Atlanta contributed to this report .
The two sides trade accusations over who caused ships to collide . The incident follows a previous high seas clash a week ago . - A Chinese fishing boat collided with an Australian vessel in the South China Sea on Monday, leaving one person dead and three others missing.