Rebels destroyed three electrical towers Friday as part of a stepped-up campaign against El Salvador's battered power system, leaving at least 40 percent of the country without electricity, the army said.

An army spokesman said members of the leftist rebel Farabundo Marti National Liberation Front, or FMLN, used explosive charges to destroy a primary electrical tower in Ilobasco, about 25 miles east of San Salvador.The spokesman said the destruction of the tower blacked out the central provinces of La Paz, San Vicente and Chaltenango.