New Delhi, Jan 7 (IANS): The principal of a school attended by a juvenile accused in the Dec 16 gang-rape case has failed to prove the claim that his age was under 18 years, police sources said Monday.

The sources said the juvenile court was not satisfied with the age-related documents presented Monday by the principal of the school in Uttar Pradesh's Badaun and asked him to produce more documents related to the juvenile's age by Jan 15.

The juvenile, one of the six accused in the gang-rape of a 23-year-old trainee physiotherapist in a moving bus here Dec 16, had done his primary education from the school.

After his arrest Dec 21, he had claimed that his age was under 18 years.

The court summoned the school principal to help in determining the juvenile's exact age.

"The charge sheet against other five accused has been filed in the Saket court. A separate charge sheet will be filed against the accused after his age is ascertained," said a police officer.