Child protection experts are investigating allegations made by Bill Bainbridge, head of Old Hall school, an 11-16 mixed comprehensive in Rotherham, in a letter to parents.
Mr Bainbridge wrote that he was aware that "shocking facts are beginning to emerge regarding the systematic sexual exploitation of 13 to 16-year-old girls in our area".
South Yorkshire police and Rotherham Council are investigating the claims. Police and the council said in a joint statement that: "We are aware of the concerns raised by Mr Bainbridge, which relate to a small number of young women who may be vulnerable to sexual exploitation.
"No formal complaints have been made in respect of an individuals."
Rotherham Council said it had a well-established procedure for dealing with problems of this kind through its area child protection committee, set up specifically to look at concerns over sexual exploitation.
Mr Bainbridge was not available for comment this week.
His school came second in the latest Rotherham GCSE tables - 55 per cent of pupils gained five or more top GCSEs, compared with an average of 41 per cent across the authority and 49 per cent in England.
Old Hall, which has 1,161 pupils, is also a technology and sports college.
Sergeant Bruce Cable of South Yorkshire police confirmed the investigation was on-going.
But the police and council said: "Because of the sensitive nature of this matter, and the lack of information at present, it is not appropriate to make any further comment."