By Alex Kirby BBC News Online environment correspondent

Japan says it could kill far more whales in the Antarctic than at present without risking their extinction.

Our calculation is that a quota of 2,000 whales could be taken for a 100 years without impact on the population

Seiji Ohsumi

It says it could safely kill about four times more minke whales annually for a century.

But extending the kill must wait for the end of the present global moratorium on commercial whaling. Until it does end, Japan says, it has no plans to kill more whales.

The claim that minke whales are abundant in the Antarctic came from the director general of the Tokyo-based Institute of Cetacean Research, Dr Seiji Ohsumi.

Numbers uncertain

He told BBC Radio Four's environment programme Costing the Earth: "Using the data we have acquired for the Southern Ocean minkes, our calculation is that a quota of 2,000 whales could be taken for a 100 years without impact on the population."

Minkes, the smallest of the great whales, can reach 10 metres (32 feet) in length in maturity. There are thought to be up to 750,000 in the Antarctic.

But the International Whaling Commission, the body responsible both for whale conservation and for regulating whaling, has recently said it does not know how many minkes there are.

Japan kills about 500 minkes a year, most of them in the Antarctic, but some also in the North Pacific, where it has begun catching small numbers of sperm and Bryde's whales as well.

Fish stock concern

It says they too are abundant, and it is researching their stomach contents to see whether they are eating commercially important quantities of fish.

Japan says all its whaling is scientific research, which the IWC allows.

A coastal whaler waits to sail

Japan's critics say it is simply a stratagem to keep the whaling fleet occupied until the IWC agrees to end the moratorium. The country defends its Antarctic programme as necessary to establish the minkes' abundance.

Many critics also allege that Japan misuses its aid budget to bribe smaller IWC members to vote its way at Commission meetings.

An independent member of parliament, Hiroshi Nakada, told Costing the Earth: "So many countries receive foreign aid money, including anti-whaling nations. But nobody minds Japan giving money to them.

"Oman, Argentina and India receive money from us, and they're always going against our cause. But no-one questions them. We don't ask anyone to vote on our side. They do it voluntarily."

Racism charge

A senior official of the country's Fisheries Agency, Joji Morishita, told the programme that Japanese people felt much of the criticism was racist.

A Buddhist priest recites a list of whales killed

He said: "We're trying to protect the principle of the sustainable utilisation of any animal, but whales are treated as an exception.

"If you say whaling is cruel you should compare it with the hunting of deer, which is accepted.

"Singling out whaling is cultural imperialism - some people would say it's racism. Norway and Iceland are also whalers, but the criticism of Japan is stronger."

Only a third of Japanese people have ever eaten whale meat, and the programme heard from one man who said increasing numbers now preferred beef instead.

Costing the Earth is broadcast on BBC Radio 4 at 2000 GMT, on Thursday, 4 October, presented by Alex Kirby.