Tens of thousands of people have marched through Mexico City in a protest against the rising price of tortillas.
The price of the flat corn bread, the main source of calories for many poor Mexicans, recently rose by over 400%.
President Felipe Calderon has said the government will clamp down on hoarding and speculation to ease the problem.
But some blame the rise on demand for corn to make environmentally-friendly biofuels in the United States.