Japanese lawmakers on Wednesday demanded the government redesign its "research" whaling programme to circumvent an international court ruling that described the programme as a commercial hunt dressed up as science.

The 40-strong fisheries committee, made up of a cross-section of members of the lower house, unanimously passed a resolution urging the administration study "all sorts of options, including walking out of the (international whaling) convention".

It said the ruling earlier this month by the International Court of Justice was "truly regrettable" but "does not necessarily prevent Japan's whaling, which is a unique tradition and culture".

The panel demanded the government find a way to continue the research operation "so as to play a responsible role as the only country in the world with a scientific approach".

The parliamentarians also demanded the government swiftly draw up a plan to replace the banned Antarctic whaling operation and fully prepare for a new programme while circulating "whale meat -- a by-product of research whaling -- appropriately as before".

Although it is a signatory to the International Whaling Convention (IWC), which bans the commercial hunting of the mammals, Japan has used a loophole that allows for "lethal research".

It said it was perfectly proper for people to consume the meat that was the inevitable by-product of the killing.

Environmentalists have maintained the science is a figleaf. Australia hauled Japan before the ICJ in The Hague over its programme.

Judges there ruled 12-4 in Canberra's favour and Tokyo said it was calling the 2014-15 hunt off.

But legal papers submitted in the United States reportedly showed the Institute for Cetacean Research, the body in Japan that carries out the whaling programme, intends to return to the Southern Ocean the following year with a redesigned scheme.

Japan on Monday insisted it had made no decision on whether to resume its Antarctic whaling.

Tokyo is also studying whether it should go ahead with another research whaling programme in the northwestern Pacific, to which the fleet was originally scheduled to sail later this month.

This hunt, which is not affected by the court ruling, operates two excursions a year, in coastal waters and offshore, from early summer through autumn.

Amid the deliberation, the whaling industry invited lawmakers to an annual buffet of all manner of whale meat on Tuesday, including sashimi.

Takashi Tanuma, a member of the Japan Restoration Party, tweeted from there: "(The whaling industry) argue the international ruling only applies to the Southern Ocean programme, but the government may expand it to operations in other regions, which must not be accepted."