If it appears that a defendant or the Commonwealth is or will be prejudiced by a joinder of offenses or of defendants in an indictment, information, complaint or uniform citation or by joinder for trial, the court shall order separate trials of counts, grant separate trials of defendants or provide whatever other relief justice requires. A motion for such relief must be made before the jury is sworn or, if there is no jury, before any evidence is received. No reference to the motion shall be made during the trial. In ruling on a motion by a defendant for severance the court may order the attorney for the Commonwealth to deliver to the court for inspection in camera any statements or confessions made by the defendants that the Commonwealth intends to introduce in evidence at the trial.