Detectives interviewing an 18-year-old man now have until Thursday to continue their investigation after a request to magistrates.
The girl was sexually assaulted at around 5pm last Friday evening shortly after she left her school bus, the number 192 from Enfield Town.
According to police, who are still appealing for witnesses, after exiting the bus on Enfield’s Bury Street, the girl walked home along Galliard Road when the attack took place over a period of two to three hours.
Her attacker has been described as a black man with afro hair, black baggy jeans and a dark grey top.
The attack was described by Detective Inspector Simon Ellershaw as “a horrific and unusual attack of a defenceless schoolgirl”.