Third World leaders recognize they should not encourage the belief that the industrial nations' resources available for aid "are inexhaustible," Peruvian Prime Minister Manuel Ulloa Elias said yesterday.

Ulloa is chairman of the Development Committee, a joint World Bank-International Monetary Fund group charged with finding ways of helping the poor nations boost their standard of living. The Development Committee regularly meets as a preliminary to the World Bank-IMF annual session which starts today.

But the Development Committee's efforts have drawn sharp criticism from many poor countries. Just at the end of last week, those less developed countries operating through the so-called Group of Twenty-Four tartly observed in a formal communique that the Development Committee "has not achieved much of significance."

Ulloa's comment on the limitation of rich nations' resources was in response to a complaint that the World Bank is considering "co-financing" with private banks to supplement the total amount of aid available.

In a "co-financing" arrangement, the World Bank and private banks cooperate in financing projects in less developed countries. But World Bank President A.W. Clausen added that a favorable consensus for "co-financing" had developed during the two-day meeting of the Development Committee despite objections raised by India.

"It's a matter of supply and demand (for funds)," Clausen said. "The consensus is that co-financing is the way to go. It's a logical step, especially for middle-income countries."

The Development Committee's communique expressed deep concern over the "grave economic problems" being faced by virtually all nations. Ulloa said the situation was "volatile and critical" and urged that the industrial nations not only take whatever steps possible to make more funds available but also lower interest rates.

He made a special plea "to do something substantive and immediate" for the sub-Saharan African countries where per-capita incomes are expected to continue to decline.

Meanwhile, West German Finance Minister Hans Matthoefer strongly supported the American view that the IMF should apply strict conditions on its loans to poor countries. Motthoefer also said that his country sees no valid reason at this point for a new issue of Special Drawing Rights. The IMF's Interim Committee on Sunday ordered a study of a compromise on SDRs that would continue a yearly allocation of the paper credit at an annual rate of SDR 4 billion (roughly $4.5 billion).

German Central Bank President Karl Otto Poehl said that he had "no reason to complain about the Reagan administration's foreign exchange intervention policy, which limits efforts to affect the market to cases of extreme urgency. The German Central Bank, he pointed out, has intervened "significantly" to bolster the rate of the German mark, and "it makes no difference whether the U.S. buys German marks or we sell dollars."

In any event, Poehl expressed agreement with the American position that intervention is not the "appropriate answer" to avoid excessive foreign exchange rate fluctuations. The main attack on this problem, he said, must be through dealing with "fundamentals," such as reducing high inflation rates.

Matthoefer said that the German government has not raised the question of high American interest rates since the bitter protest of Chancellor Helmut Schmidt at the Ottawa summit.