A helicopter flies next to the well-known restaurant and shop, Nepenthe, after picking up water to fight a wildfire in Big Sur, California, 30 Jun 2008

Firefighters in the western U.S. state of California are trying to contain more than 1,400 wildfires that have been burning for more than a week.

State emergency officials say the fire is centered in the state's northern region where 140,000 hectares have already burned.   

Officials say more than 50 properties have been destroyed, while another 7,000 homes remain under threat.

So far no deaths have been reported, however, health officials have raised concerns over poor air quality.

Some 1,800 people are working to contain the blaze with the help of at least 100 water-dropping helicopters.

On Saturday, President Bush declared a state of emergency for California and ordered federal aid to assist in firefighting efforts.

California is frequently hit by wildfires due to its arid climate and hot, dry winds. Last year, fires destroyed more than 200,000 hectares and some 2,000 homes in southern California.

Some information for this report was provided by AFP and AP.