Mexico has quietly agreed to stop shipments of beef and processed poultry to the United States after U.S. officials repeatedly raised concerns over the quality and safety of Mexican food.

The action comes less than two months after U.S. Department of Agriculture officials finally traced a U.S. salmonella outbreak to shipments of fresh jalapenos and serranos peppers grown in Mexico. It is difficult to trace illness back to the contaminated source food that caused it, so before officials traced the outbreak to Mexican peppers, they warned people away from American tomatoes, costing U.S. farmers tens of millions of dollars.

This voluntary curb on the export of Mexican meat and poultry comes ahead of any reported illnesses in the U.S. linked to Mexican meat.

"Mexico finally curbed exports of meat and poultry products from meatpacking plants with widespread safety problems, after weeks of diplomatic wrangling with American food safety regulators. A USDA audit of 11 Mexican meat plants found nearly two thirds had systemic safety problems including inadequate sanitation and government inspection procedures," Wenonah Hauter, executive director for Food & Water Watch, said in a statement Thursday. The organization is a Washington, D.C.-based non-government consumer rights group.

The group complained that despite its audit, the USDA had not acted to stop imports of questionable meat products from Mexico.

Similarly, the USDA's own data shows that problems with tainted fresh jalapenos and serranos peppers from Mexico was a longstanding problem even before the salmonella outbreak began in April.

The agency reportedly turned back dozens of cases of fresh jalapenos and serranos peppers in 2007 alone because of filth, illegal pesticides and, in at least one case, because of something poisonous.

About 84 percent of all fresh peppers eaten in the United States come from Mexico.