MEXICO CITY — Federal forces detained 10 mayors and 18 other officials Tuesday for allegedly protecting one of Mexico's most violent drug cartels in an unprecedented anti-corruption sweep in the Pacific coast state of Michoacan. Soldiers and federal agents fanned out across President Felipe Calderon's native state to carry out the operation, which an expert called a blow to politicians tied to traffickers in Michoacan. The officials, who had been under investigation for six months, allegedly leaked sensitive information and provided protection to La Familia cartel, said Ricardo Najera, a spokesman for the federal Attorney General's Office.