A father and son have pleaded not guilty to starting a massive California wildfire that destroyed 1,000 homes and forced tens of thousands of people to flee.

David Scott Smith, 66, and Travis Shane Smith, 32, are charged with reckless arson over the Caldor fire which started on 14 August.

Five people were injured and about 1,000 homes and other buildings were destroyed in the blaze which spread across three Northern California counties, covering more than 346 square miles (900 square kilometres).

The fire forced tens of thousands to evacuate the resort town of South Lake Tahoe before it was contained in October.

Both men were also charged with illegal possession of a firearm silencer and Travis Shane Smith is charged with illegal conversion or manufacture of a machine gun.

The defendants pleaded not guilty to all charges, according to Emily Idleman, assistant to the chief of investigations in the district attorney’s office.

The men were arrested Wednesday and remain in El Dorado County Jail in lieu of $1m bail each. A bail reduction hearing is scheduled for Monday.

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The criminal complaints do not specify how the machine gun and silencer tie into the fire.

Mark Reichel, the attorney for both men, said previously that the two were near where the fire started and called 911 to report flames.

“Neither one has ever been in trouble with the law in their life. They’re very law-abiding people,” he said.