A SIX-year-old boy is in a medically induced coma in a Sydney hospital after a motorcycle accident near Wagga Wagga in NSW.

A police statement says a 35-year-old man was riding his motorbike in an empty dam in the Berry Jerry State Forest about 3.20pm yesterday when he hit a young boy.

It's believed the man came over a jump and hit boy after landing.

The boy was taken to Wagga Wagga Base Hospital for treatment, but was later airlifted to The Children's Hospital at Randwick, where he remains in a medically induced coma suffering from head and facial injuries.

Police say the motorcycle rider was taken to hospital where he underwent mandatory blood and urine tests while his motorbike was seized for mechanical examination.

Detectives are continuing their investigations.