Japan has dropped its plan to kill humpback whales in Antarctic waters after strong protests led by Australia, Japanese public broadcaster NHK said Friday. An official at Japan's Fisheries Agency declined all comment on the report, which came hours after Foreign Minister Masahiko Komura warned that the growing row with Australia would be difficult to resolve.NHK television, quoting unnamed officials, said Japan "has decided to delist humpbacks from the whaling list for now due to concern about the negative impact on relations with Australia."Japan had planned to harpoon 50 humpback whales in its current expedition to Antarctica, marking the first time that Japan would hunt the animal beloved by whale-watchers since the 1960s.Japan had earlier denied remarks by Thomas Schieffer, the US ambassador to Tokyo, who said Wednesday that Japan had agreed in diplomatic discussions to stand down from its plan to kill humpbacks.Australia's new left-leaning government earlier this week stepped up the case against Japan's whaling, saying it would deploy an unarmed customs ship and a surveillance aircraft to monitor the hunt.Humpback whales, protected under a 1966 worldwide moratorium after years of overhunting, are renowned for their complex songs and acrobatic displays.The humpbacks' slow progression along Australia's coast to breed has turned into a major tourist attraction bringing 1.5 million whale watchers a year.Defying warnings from Australia and other Western nations, Japan's fleet set off last month for Antarctica on its largest ever expedition with a mission to kill 1,000 whales, most of them of the small minke variety.Japan says whaling is part of its culture, although critics point out that Japanese today eat little whale compared with other meats.Komura, the foreign minister, earlier said he hoped to speak with his Australian counterpart Stephen Smith about the growing row but doubted he would make much headway."Japan has its own culture as much as Australia does and since (whaling) involves public sentiment, it's not an issue we can resolve by convincing each other using logic," Komura told reporters."That's why it's hard," he said."Japan is conducting whaling research in line with international agreements so that's that. We have our own ideas and so does Australia," Komura said.Japan carries out the hunt using a loophole in a 1986 global moratorium on commercial whaling that allows "lethal research" on the giant mammals. Only Norway and Iceland defy the moratorium outright.Environmental movement Greenpeace and the militant splinter group Sea Shepherd have each sent a ship to Antarctic waters to try to disrupt Japan's whaling.During the last Antarctic hunt, Sea Shepherd activists threw acid onto the Japanese mother ship in a bid to disrupt the hunt, leading Tokyo to brand the environmentalists as "terrorists."