Japan has passed a law enshrining the practice of whaling and is considering upgrading its fleet of vessels in a step toward returning to the controversial commercial practice.

The new whaling bill sets out Japan's plan to one day resume commercial whaling, with one MP describing the controversial practice as "a great source of food".

Kyoshi Ejima, a member of the Upper House who voted in favour of the legislation, said Japan could become a self-sustaining food nation if commercial whaling was allowed to resume.

"This resource exists out in the world, there are minke whales down in the Antarctic Ocean that are of body weight of around 5,000 to 10,000 kilograms," Mr Ejima said.

"These are a great source of food and my position is that we should harness this for food."

The International Whaling Commission introduced a moratorium on commercial whaling in 1986, with Japan commencing its program of scientific whaling a year later.

Director of the whaling affairs office at Japan's fisheries agency, Shigeki Takaya, said the country would soon recommence the commercial practice.

"Japan's fundamental policy on whaling is to conduct scientific research in order to bring about the swift resumption of commercial whaling," Mr Takaya said.

The new law will allocate 5 billion Japanese yen, or about $58 million, every year to the whaling program.

Until now, the amount spent on whaling in Japan came from the funding for the fisheries agency more broadly.

Japan wants to end the International Whaling Commission's ban on whaling, despite heavy opposition from anti-whaling groups. ( AAP: Shannon Morris )

Mr Takaya said the agency intends to undertake this year's research program in the Southern Ocean.

"Basically, we believe whether it's whales, sharks or tuna, all marine resources should be used sustainably based on scientific research," he said.

"I think it should not be banned because of emotional or unscientific reasons."

'I think the negative response will be the same'

When it comes to public response, Mr Takaya said he is prepared for the negative reaction Japan's new legislation is likely to bring, particularly in Australia.

"Japan conducting research aiming for resumption of commercial whaling has not changed at all. I think the negative response will be the same as before," he said.

Mr Takaya says the agency will consider an upgrade to Japan's whaling ships. ( ABC News: Rachel Mealey )

"I've been following reports especially in Australia, and they're consistent as well.

"Also you say impact from the world, but the whole world is not full of anti-whaling countries — just one country's voice is not right.

"I would like you to listen to voices of many other countries."

Mr Takaya also said the agency will consider an upgrade to Japan's whaling ships.

"It's true that the mother ship of the research whaling is getting old," he said.

"If we decide to make a new vessel, we need to think carefully of the future direction of Japan's whaling."

Dolphin and Whale Network secretary-general Nanami Kurasawa said the argument there is demand for whale meat in Japan is false and there is no justification for killing whales for research.

"It's clear that this industry cannot stand on its own two feet without government subsidy," she said.