Parents of children with head knocks are asking for GP sign-off for their kids to resume contact sports, even after failing medical assessments, a GP registrar says. 

Guidelines from major sporting codes say any child who sustains a head injury needs medical assessment and paperwork signed by a doctor declaring the child is fit to return to play.

Children who fail medical assessments typically must wait 14 days before returning to the field.

But Dr Sarah Kleinman, who works in the rugby league heartland of Townsville, in north Queensland, said parents had asked her to sign the paperwork early to let children return to the field.