An 11-year-boy accused of lighting two fires at Port Stephens has been placed under house arrest.

The boy was charged yesterday over two fires, one which caused mass evacuations and destroyed more than 5,000 hectares of bushland in the Heatherbrae area last week.

The 11-year-old is accused of using a cigarette lighter to set fire to an abandoned mattress at Raymond Terrace on October 13th, and just hours later it is alleged he set fire to grass at Heatherbrae.

The first fire was extinguished but the Heatherbrae fire spread.

The court heard the boy was seen fanning the Heatherbrae fire with a tree branch.

The boy's lawyer told the Broadmeadow children's court in Newcastle, his client says another boy started the fires and he will challenge the police facts.

Despite the prosecution opposing bail, Magistrate Peter Feather granted strict bail taking into account the boy's age.

He said the boy is effectively under house arrest and can only leave home with his mother or an authorised adult.

The charges carry a maximum 14-year jail sentence.

A 15-year-old is also due to appear in court next month after being charged yesterday by police over the same fire.

He was last night charged with intentionally lighting a fire and being reckless to its spread.

The fire forced hundreds of residents to take shelter in evacuation centres and with friends and family.

Newcastle Airport was also forced to close at the height of the blaze.

Fire crews are still working to black out the Heatherbrae fire ahead of predicted worsening weather conditions this week.