Japan's whaling fleet set out for the Antarctic on Tuesday to resume a hunt for the mammals after a year-long hiatus, prompting criticism from Australia as well as key ally, the United States.

Japan aims to take more than 300 whales before the hunt ends next year and nearly 4,000 over the next 12 years as part of a scientific programme to research the whales.

The International Court of Justice (ICJ) ruled last year that Japan's whaling in the Southern Ocean should stop and an International Whaling Commission (IWC) panel said in April that Japan had yet to demonstrate a need for killing whales.

But Tokyo retooled its plan for the 2015/16 season to cut the number of minke whales it intends to take to 333, down by two-thirds from previous hunts.

"Last year, regrettably, the ICJ made its ruling and we were unable to take whales," said Tomoaki Nakao, the mayor of the western city of Shimonoseki that is home to the whaling fleet and part of Prime Minister Shinzo Abe's election district.

"There's nothing as happy as this day," he told the fleet's crew at a ceremony prior to their departure.

Shortly before noon the ships sailed away under a clear blue sky, with family members and officials waving from the shore. The hunt is expected to last until March.

Japan, which has long maintained that most whale species are not endangered and that eating whale is part of its food culture, began what it calls "scientific whaling" in 1987, a year after an international whaling moratorium took effect.

The meat ends up on store shelves, although most Japanese no longer eat it.

Officials, including Abe, have long said their ultimate goal is the resumption of commercial whaling - a pledge Abe repeated in a message read at the pre-departure ceremony.

Australia and key Japanese ally the United States both opposed the hunt.

"We believe that all of Japan's primary research objectives can be met through non-lethal activities and continue to oppose their scientific whaling programmes," said Russell F. Smith, the U.S. commissioner to the IWC.

Environmental activists also condemned the move.

"It is completely unacceptable for the Japanese government to ignore the International Court of Justice," said Junichi Sato, executive director of Greenpeace Japan, in a statement.

"This is not 'scientific research,' this is straight up commercial whaling."