Mexico's President Felipe Calderon has pledged to intervene to tackle the soaring price of tortillas, the flat corn bread which is a local staple.
The diversion of cheap imported US corn is worsening the situation
The price of tortillas, the main source of calories for many of Mexico's poor, rose by more than 10% last year.
Mr Calderon said the government would clamp down on speculators and search for cheaper providers of corn.
But he ruled out imposing subsidies or price controls, which were lifted in the late 1990s.
"We will take all the measures within reach of the federal government to avoid escalating prices," Mr Calderon said.
In the meantime Mr Calderon has told his agriculture secretary to import corn to ease the problem.
"I don't care if it's brought from thousands of kilometres away, the most important thing is that this [shortage] is not used as an excuse to raise prices," he said on Thursday.
Earlier this week, angry housewives heckled Mr Calderon at his public appearances, pleading with him to bring tortilla prices down.
"When there isn't enough money to buy meat, you do without," one woman in Mexico City, Bonifacia Ysidro, told the Associated press. "Tortillas you can't do without."
Ms Ysidro said she paid 25 pesos - about a sixth of her family's daily income - for enough tortillas to feed her family of six.
On Thursday, government officials from the Federal Competition Commission said that they were investigating claims that tortilla companies around the country were manipulating prices and restricting supplies to boost profits.
"If we detect monopolistic practices, we could impose fines of up to 70m pesos [$6.4m]," commission director Eduardo Perez Motta said in a statement.
Under the 1994 North American Free Trade Agreement, Mexico used to get cheap corn imports from the US, but Mexico's Economy Minister Eduardo Sojo said that with more US corn being diverted into ethanol production, supply was dwindling.