Britons at risk from deadly wildfires across California have been urged by the Foreign Office to follow the advice of the state authorities.

The death toll has risen to 11 but emergency authorities have admitted they expect that figure to rise.

A state of emergency has been declared in Napa, Sonoma and Yuba, where 1,500 properties have been destroyed.

Evacuation orders are now in place in several areas across the state – where more than 20,000 people have been forced to flee their homes – after the fires started on Sunday night.

In a statement, the Foreign Office said: “Wildfires can spread swiftly so always remain cautious.

“Some infrastructure has been damaged – including phone communications and internet access.

“Follow the instructions issued by the local authorities and obey all evacuation orders.”

The state fire service reported how 15 separate wildfires burnt across 73,000 acres – thanks to a combinations of high winds, low humidity and the dry weather.