In the poor and tiny village of Ubaque in the highlands of Colombia, the local women were enrolled in a foreign aid program. Using butter imported from Bogota, they learned how to bake meringue pies.

Mayra Buvinic, president of the Washington-based International Center for Research on Women, offered that anecdote to illustrate one of the pitfalls of foreign assistance. She and many of the other 1,600 experts on international development meeting here this week grappled with the question of the effectiveness of foreign aid.

Some scholars argue that it exacerbates income disparities while propping up dictatorships and impeding new paths of development. But the verdict at the 25th world conference of the Society for International Development, with delegates from 60 countries, was that foreign aid helps, notwithstanding many problems, and that more is needed desperately.

Many would like to see the United States contribute far more to the least developed nations, such as Mali, Chad, Bangladesh and Bhutan.

After increases in the 1960s and 1970s, foreign aid given worldwide to low-income countries has declined in the last few years after adjustment for inflation, former World Bank president Robert S. McNamara told the conference in a call for increased aid. At the same time, developing nations are facing even greater stresses.

The United States consistently has been the largest single donor to developing countries, giving $7.1 billion in 1980, but, as a proportion of gross national product, its contribution ranks 12th among 17 industrialized countries, according to World Bank figures.

The U.S. contribution in 1980 was .27 percent of the gross national product, and McNamara said that figure has dropped to .2 percent. In comparison, nations in the Organization of Petroleum Exporting Countries contribute 1.36 percent of GNP, and Soviet bloc countries donate .12 percent.

Amid the panels, speeches and luncheon discussion at the conference, one frequent subject was waste and poorly conceived projects. Buvinic told of visiting an aid project in a tiny village in the Bolivian Sierras where women tended flocks of llamas and sheared them with broken glass.

"The women wanted classes on shearing and on veterinarian technology," she said. Instead, they were "taught cooking and how to make papier-mache flowers."

Buvinic said such projects are common because they are cheap, easy to implement and politically safe.

Others cited examples of assistance projects that worked. Atlanta Mayor Andrew Young, former ambassador to the United Nations, said he had visited a project near Kano, Nigeria, where corn yields were one-third higher than in the United States. The only misfortune, Young said, was that more aid was not allocated to finance similar projects elsewhere in western Africa.

"I don't think you can say aid ever fails," Young said. "Essentially, it isn't always used as efficiently as it could be."

Others endorsed aid but were more cautious. Robert J. Berg, former chairman of an evaluation committee of the Organization for Economic Cooperation and Development, said his research suggested that aid seems "to do more good than harm." He then qualified that statement even further, provoking a ripple of laughter from the audience.

Although OPEC countries contribute a large proportion of their GNP to poorer nations--OPEC's Arab members contributed 2.3 percent in 1980--critics also have noted that OPEC's soaring oil prices in the 1970s were a major cause of distress in developing nations.

Iraq's Fadhil Chalabi, OPEC's deputy secretary general, denied these charges in a speech, and said OPEC's aid had made up for higher oil prices Third World countries must pay.

He said inflation seeping in from the industrialized world was a more important problem for poor nations, and called on the West to join with OPEC in expanding aid programs.