A blaze that has scorched some 43,000 acres (17,400 hectares) and destroyed dozens of homes near California's famed Big Sur coast was sparked by an illegal, unattended camp fire in a state park, authorities said on Tuesday.

The so-called Soberanes Fire, which erupted on July 22, began as a small blaze, 2 feet (60 cm) in diameter, ignited by unknown individuals in a section of Garrapata State Park that was closed to camping and campfires, according to US Forest Service spokesman Don Jaques. No arrests have been made, he added.