More than half of all calls made to the NSPCC about child abuse cannot be referred to the police or social services due to lack of information, the charity has revealed.
The organisation is launching new guidance on how to protect children from sexual abuse as well as advice on how to report suspected cases.
Parents play an essential role in reporting abuse, as they are able to spot less obvious abuse, the children's charity said.
Currently, more than a third of calls to the NSPCC about child sexual abuse are made by the child's own parent.
While teachers, neighbours and family friends are able to spot physical abuse which leaves marks and bruises, the guidelines highlight how parents may often hesitate to provide enough detail to allow further action to be taken, because in many cases of sexual abuse the abuser will be a relative or well known to the caller.
Research shows that 80% of offences take place in the home of either the offender or victim. Some parents are also concerned that they will not be believed, or that they may be blamed for not preventing abuse.
John Cameron, head of the NSPCC's helpline, said: "Whilst we have seen a surge of calls in recent weeks relating to the Jimmy Savile revelations, we shouldn't forget that the majority of sexual abuse is committed by someone close to the child. As a parent, knowing or suspecting your child is being sexually abused can be incredibly traumatic.
"But to protect children, people need to act and we provide sensitive professional help and support. Even if they feel they have dealt with the situation themselves and their child is safe, other children may still be at risk from the abuser.
"When parents or others report abuse, whether it's the NSPCC, children's services or the police, professionals will work with them to protect the child, help them overcome the abuse and bring the abuser to justice. Our new leaflet helps parents to take the difficult steps in identifying and reporting sexual abuse," he added.
The NSPCC's new guidance for parents and carers, 'What can I do? Protecting your child from sexual abuse', is available now to download from www.nspcc.org.uk.