By Michael Fiala

CARMEL-BY-THE-SEA, Calif. (Reuters) - A deadly blaze near California's Big Sur coast could widen to more than five times its current size and has destroyed some 60 homes, threatened hundreds of others and spurred mass evacuations, authorities said on Saturday.

The so-called Soberanes Fire, which started on July 22 and is burning just south of the oceanside town of Carmel-by-the-Sea, has roared through nearly 32,000 acres (13,000 hectares) of drought-parched chaparral, grass and timber in the Los Padres National Forest.

The blaze is estimated to have a final size of 170,000 acres (265 square miles), according to California Interagency Incident Management Team 1, which is comprised of federal, state and local authorities. The cost of fighting the fire is now at about $6 million a day, it said on its Twitter feed.

The estimated final size of the blaze is roughly equivalent to the size of Singapore.

More than 5,000 personnel were fighting the blaze that has so far destroyed 57 homes and 11 outbuildings, with at least five other structures damaged, officials said on Friday evening. Some 2,000 other structures were threatened, officials added.

More than 500 fire trucks along with 14 helicopters and six air tankers have been deployed to fight the blaze. Containment stood at 15 percent on Friday, up from 10 percent in the previous few days.

Mountainous terrain combined with extremely hot, dry weather has hampered efforts by firefighters to hack buffer lines through dense vegetation around the perimeter of the blaze, officials said.

The fire threat has prompted authorities to close a string of popular California campgrounds and recreation areas along the northern end of the Big Sur coastline, including Julia Pfeiffer Burns State Park and Point Lobos Natural Reserve.

Highway 1, the scenic route that winds along seaside cliffs overlooking the Pacific, remained open, though motorists were advised to allow for traffic delays caused by firefighting equipment entering and exiting the roadway.

The blaze took a deadly turn on Tuesday when a bulldozer operator hired by property owners to help battle the flames was killed as his tractor rolled over. It was the second California wildfire death in a week.

(Writing by Jon Herskovitz in Austin, Texas and Brendan O'Brien in Milwaukee; Editing by Dale Hudson)