Ambrosio Soto, the mayor of a township that includes known drug trafficking haven Ciudad Altamirano, was killed late Saturday, making him the second mayor to be killed in Mexico over the weekend.

"Yesterday, our friend Ambrosio Soto, president of the Pungabarato municipality, was killed, besieged by organized crime," Mexican Senator Miguel Barbosa said in a statement on Sunday.

Soto was visiting a town in Michoacan state near the Guerrero state border, where his township is located.

Guerrero state spokesman Roberto Alvarez said gunmen blocked a highway with pickup trucks near the borderline in Michoacan, and then proceeded to open fire on Soto's vehicle.

Alvarez added that two federal officers were wounded in the attack.

Mexican authorities provided Soto with additional security, including a federal police detail, after he made a request over a year ago, Barbosa said.

A local drug gang reportedly threatened the mayor after he refused to turn over part of the township's operating budget as a payment for protection.

75 mayors killed in drug violence

Meanwhile, police on Sunday arrested six men in connection with the murders of Domingo Lopez Gonzalez, mayor of San Juan Chamula, two town officials, a municipal government driver and a resident.

Gunmen opened fire on the mayor during a multi-day protest in the central square of San Juan Chamula on Saturday.

The leftist Democratic Revolution Party said 75 mayors have been killed in the last decade due to drug-related violence in Mexico.

ls/cmk (AP, AFP, EFE)