Japan Expected to Dwarf U.S. Environment Aid : Summit: Its likely pledge of up to $8 billion over five years would outstrip Washington’s vow of $1.25 billion.

RIO DE JANEIRO — Moving to assert itself at a major environmental summit meeting here, Japan is expected to announce the commitment of $6 billion to $8 billion in new environmental assistance for developing nations over the next five years.

By contrast, the United States has pledged $1.25 billion over the same period--less than a quarter of what Japan is planning.

With the United States reluctant to embrace an aggressive agenda at the United Nations Conference on the Environment and Development, the aid package would be yet another step by Japan to try to fill a leadership vacuum.

Japanese Prime Minister Kiichi Miyazawa is to announce the aid for environmental projects in the Third World later in the week if he is able to break away from domestic parliamentary deliberations.

A spokesman for the Japanese delegation refused Saturday to disclose Japan’s intended contribution, but a knowledgeable source confirmed the range in an interview with The Times.

Already at the top in pollution-control and energy-efficiency technology, Japan stands to reap substantial profits from efforts under way here to spur poorer nations to develop in an environmentally benign fashion.

Prevented by domestic restrictions from taking a lead militarily, Japanese officials hope to carve out a prominent future role on environmental issues. Recent polls show that the environment is a major concern of the Japanese electorate.

“I believe that Japan’s primary duty to the global environment is to take a lead in reforming our society to an environmentally sound and sustainable one,” Japanese delegate chief Shozabura Nakamura told diplomats from 178 nations.

Japanese diplomats have been quietly effective at helping forge agreements in summit negotiations. For example, they suggested the compromise that eventually won U.S. support for a treaty on global warming.

Members of the delegation bristle at any suggestion that Japan is using its technological lead to wield influence or is pushing for environmental reform out of self-interest.

“As a general proposition, Japanese are not in the habit of coming to the forefront and saying, ‘We assume leadership,’ ” said Japanese delegation spokesman Sadaaki Numata. “We don’t have the habit of riding a moral high horse.”

Rather, he said, the Japanese want to lead by effective diplomacy and a good environmental example both at home and abroad.

Japan already has committed itself to building pollution-control centers in Thailand, China and Mexico. Some Japanese grants require recipients to purchase Japanese products, but most environmentally related aid is untied, Numata said.

He acknowledged, however, that unrestricted assistance may still end up benefiting Japan because it insists that aid projects comply with strict environmental standards. To meet these criteria it may require the use of technology in which Japan excels.

The Japanese already have spent about $3.2 billion over the last three years on global environmental assistance. The United States has spent about $500 million a year.

But the Japanese want to lead politically as well as financially, and resent being seen only as a deep pocket.

“People accuse us of using checkbook diplomacy,” said Numata. Although its citizens want Japan to exert itself in environmental affairs, “we still resent the idea that Japan is being looked at as the world sugar daddy,” he said.

The Japanese, unlike the United States, supported an early effort to produce a stronger global warming treaty. Japan also is planning to sign a pact opposed by the Bush Administration to conserve plants, wildlife, organisms and their habitats.

Throughout the negotiations, Japanese diplomats have served somewhat as ombudsmen in helping communicate the positions of the Third World to the richer countries.

“They are the most discreet delegation” among the industrialized countries, said Richard Mott, a World Wildlife Fund official who has been monitoring the talks. “They operate very vigorously backstage . . . .”

To maintain a public presence, the Japanese government is attempting to hold briefings regularly here for the international press. But conservationists have been disappointed that the prime minister has not yet pledged to attend. He is involved in a controversial domestic parliamentary proceeding over whether Japan will send troops on future United Nations peace-keeping missions.

High-level Bush Administration officials have smarted at unfavorable comparisons with the Japanese on summit issues and derided a voluntary commitment by Japan to stabilize emissions of carbon dioxide by the year 2000.

Carbon dioxide, released by the burning of coal, oil and gas, is believed to be the primary contributor to projected and possibly highly destructive global warming.

The Administration has refused to commit to such a stabilization target, and officials have described Japan’s pledge as an empty promise that is based on nuclear power plants Japan will be unable to build, at least in the near term.

Others take the Japanese commitment more seriously. William A. Nitze, president of the Alliance to Save Energy, visited Japan recently and came away impressed at Japan’s energy conservation technology.

He said the Japanese are in “pretty good shape” to build more than half of 40 nuclear plants proposed at existing nuclear sites. However, he said, they may have trouble winning public acceptance for the rest.

But Nitze said the Japanese also possess other technology, including natural gas turbine systems that recycle heat to produce more electricity, which makes him optimistic about Japan’s future success.

“I have lived in Japan, and the Japanese are better than any people I know in meeting quantitative challenges of this kind by taking a number of coordinating steps simultaneously,” said the president of the nonprofit environmental, consumer and business group.

In the past, the Japanese have had a mixed reputation among conservationists. Although lauded for its anti-pollution efforts and energy efficiency, Japan has been criticized for whaling, using fishing drift nets that kill dolphins and for helping deplete tropical forests by importing substantial amounts of tropical timber.

Numata said the Japanese construction industry has pledged to try to reduce its use of tropical timber, but conservationists are far from satisfied. He also said the Japanese will comply with a United Nations resolution calling for an end to drift nets, and they now only take whales from the Antarctic, where he contends they are plentiful.

“In most cases, I think Japan has probably cleaned up its act, except in the case of whaling,” said Cecilia Song, the spokeswoman for the Worldwide Fund for Nature in Tokyo.

The Japanese take whales for scientific research, which is allowed under international rules, and then sell the meat for food, she said.

Japan achieved its lead in environmental technology--followed by Germany and the United States--after the government instituted strict controls to combat widespread pollution during the 1960s and 1970s. Almost totally dependent on fuel imports, Japanese industry had to become more energy efficient to be competitive.

A top summit official has estimated that environmental initiatives being negotiated here would require $125 billion a year in aid but has asked for $5 billion to $10 billion as a first step.

Environmental lobbyists are publicly calling for more assistance to enable the Third World to develop without resorting to cheap, polluting technology. But these activists worry privately that a huge and sudden influx of money might be wastefully spent because there are not enough mechanisms yet in place to administer it effectively.