Frozen chicken should be cooked thoroughly to a safe minimum internal temperature of 165 degrees Fahrenheit (74 degrees Celsius) and the best way to do that was with a food thermometer, the U.S. Department of Agriculture (USDA) said Monday.

The federal agency is linking the Salmonella sickness of 32 people in 12 to frozen dinners in which chicken is raw. Despite specific cooking instructions, the dinners were microwaved that results in uneven heat, which is not enough to kill the Salmonella bacteria, the agency said.

Frozen, raw stuffed chicken products labeled are sold under the name "chicken cordon bleu" or "chicken Kiev". They also include chicken breasts stuffed with cheese or vegetables that often come in the form of breaded and pre-browned chicken breasts.

The danger comes from cooking the chicken in the microwave, and not cooking it fully, the USDA said adding that it could lead to serious illnesses, such as Salmonella infection, which could be life-threatening. Most vulnerable groups include infants, the elderly and other people with weakened immune systems. Symptoms of salmonella include diarrhea, fever and abdominal cramps.