Two years of unconventional thinking, debating and global travel by a diverse group of international politicians, business people and economists has produced new ideas for cooperation between the industrial countries and the underdeveloped Third World.

"Urgent and drastic steps must be taken" to reduce growing conflict and share wealth, technology, food and natural resources "to avert impending catastrophe," said the group's chairman, former West German chancellor Willy Brandt.

Brandt and others in the group previewed here some of the conclusions and recommendations of the Independent Commission on International Development, better known as the Brandt commission. Its final report, approved last weekend at Leeds Castle near here, will be made public after it is presented to United Nations Secretary General Kurt Waldheim in February.

Among the commission recommendations unveiled are:

A new World Development Fund which, unlike the present World Bank in Washington, would involve both Communist and noncommunist countries and make loans for more general use by needy countries rather than only for specially earmarked projects. Loan money could be used, for example, to correct critical balance of payments deficits.

A commitment by rich countries to live up to their promise to devote .7 percent of their gross national product to aid for international development and to increase that aid to 1 percent of gross national product by the end of this century.

An international tax on trade, minerals extracted from the sea and weapons sales (which Brandt called "the most wasteful of all forms of spending") to raise more money for poorer countries.

An international agreement on the production, pricing, supply and conservation of oil and their energy resources to benefit both producing and consuming nations by assuring regularity of price increases, security of supply and commitment to conservation.

An efficient international food program to increase production and assure distribution to the underfed.

A "new kind of summit conference" of world leaders to generate political backing for these and other reforms of the global economy.

The commission, conceived by World Bank president Robert McNamara, concluded that such reforms could help both developing countries by providing them badly needed financial, technological and other help, and industrialized nations by providing them with new markets and assured sources of raw materials.

"The world north and south, its industrialized and its developing nations, have a far greater mutual interest than they commonly recognize in achieving economic revival," the report said.

Despite its ultimate agreement on this premise, the commission's own internal "North-South dialogue" was reportedly stormy at times as its members met in both rich and poor nations and debated the implications of what they saw.

Among the commission's 18 members were four former heads of state -- Brandt, former Swedish prime minister Olof Palme, former British prime minister Edward Heath and former Chilean president Eduardo Frei -- who themselves spanned the political spectrum from left to right.

Also included were political, business and economic figures from the United States, Canada, France, Japan, Kuwait, India, Indonesia, Algeria and Tanzania. The U.S. members were Peter S. Peterson, former commerce secretary and board chairman of Lehman Brothers Kuhn Loeb Inc., and Katharine Graham, chairman of the board of The Washington Post Co.

Unanimous approval of the commission's conclusions was made possible when Heath a leading spokesman for the industrial West, and Shridath Ramphal of Guyana, the secretary-general of the Commonwealth, who emerged in the same role for the Third World's representatives, assumed the task of writing a compromise final report.