(a) General rule.--An informal hearing shall be held promptly by the court or master and not later than 72 hours after the child is placed in detention or shelter care to determine whether his detention or shelter care is required under section 6325 (relating to detention of child), whether to allow the child to remain in the home would be contrary to the welfare of the child and, if the child is alleged to be delinquent, whether probable cause exists that the child has committed a delinquent act. Reasonable notice thereof, either oral or written, stating the time, place, and purpose of the hearing shall be given to the child and if they can be found, to his parents, guardian, or other custodian. Prior to the commencement of the hearing the court or master shall inform the parties of their right to counsel and to appointed counsel if they are needy persons, and of the right of the child to remain silent with respect to any allegations of delinquency. If the child is alleged to be a dependent child, the court or master shall also determine whether reasonable efforts were made to prevent such placement or, in the case of an emergency placement where services were not offered and could not have prevented the necessity of placement, whether this level of effort was reasonable due to the emergency nature of the situation, safety considerations and circumstances of the family.

(b) Rehearing.--If the child is not so released and a parent, guardian or other custodian has not been notified of the hearing, did not appear or waive appearance at the hearing, and files his affidavit showing these facts, the court or master shall rehear the matter without unnecessary delay and order release of the child, unless it appears from the hearing that his detention or shelter care is required under section 6325.