The teacher, who triggered a week-long Europe-wide search when he ran away with a 15-year-old student, faces charges of child abduction in England.
He was arrested in the southwestern French city of Bordeaux on September 28 and extradited last month after a European arrest warrant was issued.
After hearing the young girl, who can not be named for legal reasons, a court in Maidstone, Kent, has asked that the warrant be changed to include sexual charges.
The 30-year-old maths teacher could now face 14 years in prison instead of seven.
Court sources in Bordeaux told AFP that the British request would be examined by the end of the month.
Existing European agreements stipulate that a suspect can only be tried on the charges listed in the arrest warrant.