Thirteen people were killed in the restive Mexican states of Michoacan and Guerrero, Mexican authorities said on Sunday, amid feuds between rival drug gangs that have racked the country.

The prosecutor's office of the western state of Michoacan said in a statement the heads of six men were found in front of a business in the town of Jiquilpan, near the border with Jalisco, where drug traffickers from the Jalisco New Generation Cartel (CJNG) operate.

A threatening message signed by the New Michoacan Family (NFM), a rival criminal group, was left next to the heads, the prosecutor´s office also said.

In another episode in the mountains of Atoyac in the state of Guerrero, home to the resort town of Acapulco, seven people were killed by gunfire, including three police officers, state police said.