San Francisco/Washington - California officials moved to clamp down on fireworks for US Independence Day celebrations Friday as cool, humid air raised hopes for calming fires that have closed down access to the spectacular ocean-side landscape of Big Sur.

The restriction on fireworks put a crimp in Fourth of July celebrations for California and other parts of the west fighting wildfires. Police forces have declared zero tolerance for do-it- yourself fireworks, because of the potential for igniting new blazes. They intend to enforce the ban with extra vigilance.

California Governor Arnold Schwarzenegger has told Californians to boycott all privately-sold fireworks, including charity organizations that count on the income for their good works.

"I know that the people that are selling all this stuff are going to go crazy now when I say this, but don't buy any of the fireworks," he was quoted as saying by the New York Times.

The Big Sur fire burned another 404 hectares overnight, the San Francisco Chronicle reported, expanding on the 212 square kilometers already burning since it was started by lightning on June 21.

It is currently about 5 per cent contained as more than 1,600 firefighters worked to contain the blaze. Fire officials indicated they did not expect the fires to be contained until July 30.

"We had a really good night last night," Rudy Evenson, information officer for the agencies battling the fire, was quoted as saying. But he added "this is a long-term fire. Today's a new day, tonight's a new night."

To date, 20 structures have been destroyed in the Big Sur fire, and another 1,300 homes were threatened, media reports said.

A 64-kilometre stretch of the famous Highway 1 remained closed, and hundreds of people remained evacuated.

Fires also burn elsewhere in the state amidst an unseasonably early outbreak. Officials put the total number of fires for the state at 1,781, with a total of 34 homes destroyed to date.

Across the state, more than 20,000 personnel were fighting flames, backed by 1,500 fire trucks and more than 100 aircraft dropping water.

California Governor Arnold Schwarzenegger on Thursday extended extended California's state of emergency to Santa Barbara county where a wildfire threatened the coastal community of Goleta.

The fires are causing huge concern, coming early in the season due to low rainfall over the winter and spring, which left brush tinder dry at least two months ahead of schedule.

California's worst fire months are usually September and October, when hot, dry inland winds blow across the south of the state. Last year, more than 2,000 homes were destroyed by the late summer fires, causing more than 3 billion dollars in damage. (dpa)