BERLIN - Germany's food scandal deepened on Friday as regional authorities shut down more than 4,700 farms after tests found animal feed contaminated by a chemical that causes cancer.

Fears also grew that tainted products may have entered the food chain earlier than thought, as tests on animal fats at the firm at the center of the scandal reportedly showed the contamination dates back as far back as March last year.

A total of 4,709 farms and businesses were closed, including 4,468 in Lower Saxony, a state in northwest Germany, according to the Ministry of Agriculture on Thursday.