Bolivian President Evo Morales on Monday criticized "some South American presidents" for supporting the use of biofuels, which he said are responsible for high food prices and global hunger. Visiting the United Nations while fighting autonomy referendums called by the opposition at home, the Bolivian president said the increased use of farmland for fuel crops was causing a "tremendous increase" in the price of food -- especially of wheat, which has made bread more expensive.