Speaking at the United Nations, the Bolivian president, Evo Morales, said the increased use of farmland for fuel crops was causing a "tremendous increase" in food prices.
The Reuters news agency reported that the Peruvian president, Alan Garcia, called on developed countries to grow more food. In the last few months, food prices in Peru have run ahead of the country's general rate of inflation.
Their attack coincided with a report published today by the environmental group Friends of the Earth warning the EU of the perils of expanding biofuel use in Latin America. Last year the EU agreed on a target of 10% biofuel use for transport by 2020.
The report says the certification schemes being set up by some South American countries to ensure sustainable production of sugar cane and soya bean crops are not enough to prevent damage to the environment and "fail to address the biggest problems" caused by the cultivation of land currently covered by forests or smaller farms.
In his UN comments, Morales criticised "some South American presidents" for pushing biofuels. The Bolivian president did not name them but his views are in sharp contrast to those of the Brazilian president, Luiz Inacio Lula da Silva, who has said developing countries have enough land to produce both food and biofuels.
Morales called on developed nations to accept that problems created by biofuels in developing countries were partly their responsibility. After his speech, he told a news conference that "it is not an internal problem, it is an external problem".
"This is very serious," he said. "How important is life and how important are cars? So I say life first and cars second."
In his UN speech, Morales called for the International Monetary Fund and the World Bank to take action against the biofuel industry "in order to avoid hunger and misery among our people".
Reuters reported Garcia as saying biofuels were "creating very serious problems for countries that have to import these (food) products. We believe there are alternative energies that do not put the world's food in danger."
Peru's government has been forced to hand out food to the poorest in the country's capital, Lima, because of the crisis caused by rising food prices. It has cut tariffs and raised interest rates to try to curb inflation, which rose 4% last year.
Both leaders are facing challenges to their authority. This month, Garcia's approval rating sank to 26% - the lowest since he took office in 2006 - and 57% of those polled said rising prices was the main reason for their disapproval.
Morales, meanwhile, is fighting opposition leaders in four eastern provinces who want significant autonomy from the central government.
© 2008 The Guardian