ACAPULCO, MEXICO, NOV. 27 -- The presidents of eight Latin American countries today opened a two-day summit meeting with demands for fairer treatment of their debt problems by foreign creditors and a greater role in decision-making on international political and security matters.

The presidents of Mexico, Brazil, Argentina, Peru, Colombia, Uruguay, Venezuela and Panama gathered in this Pacific Coast resort for what several of them noted was the first major Latin American summit to be convened without the involvement of the United States.

After an opening speech by Mexican President Miguel de la Madrid, the conference host, each head of state addressed the gathering publicly before heading into close-door sessions.

"For the first time in our history, we are meeting on our own initiative to define a political plan that will effectively serve the goal of unity that calls us together," said Argentine President Raul Alfonsin.

Peruvian President Alan Garcia, who has suspended interest payments on his country's foreign debt and nationalized its banking system, called on Latin America to "abolish the monetary dictatorship of the dollar that has been imposed on us for more than 40 years."

He also declared, "It is time for Latin America ... to call the attention of the world's industrialized countries to the imperative of reconstructing the world economic system."

Indeed, the occasion was marked by a renewal of some of the North-South rhetoric that flourished during the 1970s, when industrialized and developing countries held inconclusive negotiations revolving around Third World demands for a "new international economic order."

But some of the tougher rhetoric at this meeting, including demands for a unified Latin American approach to debt renegotiations, appeared unlikely to be translated into concrete resolutions because of divisions among the eight in their debt-payment policies, conference sources said.

In apparent references to arms control talks between the United States and Soviet Union, two presidents expressed frustration that Latin America was not consulted. Brazilian President Jose Sarney said Latin America was "determined to participate fully in the great international decisions on political and security matters." And Alfonsin lamented that the region has been "unacceptably left out of the world's great decisions."

For their part, U.S. officials have expressed concern that the Group of Eight, as the participating countries are known, not become a substitute for the Organization of American States, which includes the United States as well as the countries of Latin America. The eight consist of the members of the Contadora Group -- Mexico, Panama, Colombia and Venezuela -- formed in 1983 to try to make peace in Central America, and of the nations of the Contadora Support Group, which was formed 1985 at the behest of Peru and includes Brazil, Argentina and Uruguay. Together the eight account for 80 percent of Latin America's population and a large part of its $400 billion foreign debt.

In opening the summit, De la Madrid noted the "high social and moral cost" of Latin America's foreign debt, but rejected the idea of a "political negotiation including all those involved" in the issue. He added, however, "today we cannot postpone adjusting debt service payments to the capacity to pay and the necessity for growth in Latin America. We do not dismiss international commitments, but our primary duty concerns the present and future well-being of every one of our people."

Before the meeting, Mexican Foreign Secretary Bernardo Sepulveda said the eight might discuss ways to get better terms from their creditors, but that each country had "a rather unique relationship with world financial institutions" and that joint negotiations were "impractical."

Mexico, whose $100 billion foreign debt is the second-largest in the developing world, has prided itself under De la Madrid with keeping up payments and gaining a reputation as a "model debtor."

Among those expressing support for a harder line on debt and a united approach in negotiations were Peru's Garcia, Brazil's Sarney and Panamanian President Eric Arturo Delvalle.

Sarney said in his speech that, relatively speaking, Latin America today is in worse shape than at the beginning of the century. He said the region's average per capita income now barely exceeds that of 1975 and that Latin America "has turned into a net exporter of capital." Brazil has a foreign debt of $112 billion, the developing world's largest.

Delvalle, who serves as a figurehead president in a regime run by Panama's military strongman, Gen. Manuel Antonio Noriega, called for debt negotiations as a "Latin American bloc" and for the establishment of debt-service payments on the basis of the debt's market value.

He also took the opportunity to accuse the United States of "political and economic aggression" against his country following a vote by the Senate Foreign Relations Committee in favor of cutting off economic and military aid to Panama until it ends abuses by the Defense Forces and restores constitutional rights.