POLICE have spoken to more than 30 former female pupils of Chetham's School of Music who have reported historic sexual abuse.
The investigation is focusing on "a pool of about 10 offenders", said Greater Manchester Police (GMP).
The women came forward following the sex abuse trial of the prestigious Manchester school's ex-music director Michael Brewer.
Brewer was jailed for six years in March after he was found guilty of indecently assaulting ex-pupil Frances Andrade, 48, more than 30 years ago when she was 14 and 15.
Mrs Andrade killed herself at her home in Guildford, Surrey, a week after giving evidence against him.
The trial heard allegations that sexual activity between teachers and pupils at Chetham's was not uncommon.
Police have made one arrest so far as part of their probe which was launched in February.
Former Chetham's violin teacher Wen Zhou Li, 57, now a professor at the Royal Northern College of Music (RNCM), was held in February on suspicion of rape and is on bail pending further inquiries.
Detective Chief Inspector Jamie Daniels, from GMP's Protective Services Division, said: "This is a significant inquiry in terms of potential number of offenders and number of victims.
"We are supporting each and every person who has come forward and made a complaint to us as best we can and I must credit them all for having the courage to face demons that have been haunting them for many, many years.
"This has been a high-profile investigation from the off and due to the complexities and sensitivities involved cannot and will not be rushed.
"I want to reassure the public that I am absolutely committed to getting justice for these women, many of whom have been spurred on by the bravery shown by Frances Andrade in the case against former teacher Michael Brewer.
"I also want to reassure everybody that where we have identified immediate safeguarding concerns the appropriate steps have been taken in partnership with other organisations.
"Chetham's and other establishments have and continue to provide help and support at what is clearly a very difficult time for their respective staff and pupils.
"It goes without saying that if anyone has been a victim of any offence or has any information that can assist this investigation I would urge them to get in touch."
Police added they are also investigating a dozen more third party reports of abuse at Chetham's that have been made to them.
Yesterday, Channel 4 News reported that sexual abuse and inappropriate behaviour took place at five of the UK's specialist music schools over a 40-year period.
It named Chetham's and also the Yehudi Menuhin School in Surrey.
The allegations include claims that pianist Marcel Gazelle, who helped found the Surrey school, sexually abused pupils as young as 10 in the 1960s.
Mr Gazelle died in 1969. His family said he was a good man and they were surprised by the allegations, which they dispute.
The Yehudi Menuhin School said it was "shocked and saddened to learn of the allegations".
The school told Channel 4 News: "We have checked the records which survive from 50 years ago and can find nothing about any concerns expressed at the time.
"In accordance with our policies we have reported these serious allegations to Surrey Police."
Another woman who was a pupil at a music school in the 1990s told the programme her teacher flirted with her frequently, before making a pass at her after a lesson at his home.
At least three pupils at the same school say they were sexually involved with the same teacher, Channel 4 News reported.
The teacher no longer works at the school, though he continues to teach elsewhere, the programme said.
Surrey Police confirmed they have been contacted by the Yehudi Menuhin School following "allegations of historic sexual abuse against a member of staff who is now deceased".
A spokesman said: "The force is liaising with the school and would encourage anyone with concerns to contact us.
"Surrey Police treats any allegation of this nature seriously and have officers who are specially trained to support victims of sexual assault."
It is understood the 10 key suspects either taught at Chetham's, the RNCM or privately.
Some 39 people have been investigated so far by GMP - of which five are believed to have died.
Twelve individuals are the subject of third party reports and another 12 relate to matters that either do not reach a criminal threshold, or where statutory limits do not allow for a prosecution to take place, or are matters that will be passed to another police department to investigate.
In a statement, Chetham's School of Music said: "We have been in regular contact with Greater Manchester Police throughout Operation Kiso, the official name for the police's wide-ranging investigation into allegations of abuse.
"The operation focuses on Chetham's and the Royal Northern College of Music (RNCM), but also includes investigations into events occurring outside of these two music institutions.
"When we contacted the police earlier on today they confirmed that they are currently investigating 39 individuals (some deceased) as part of the operation and that not all of these individuals taught at either Chetham's or the RNCM.
"We would like to reassure parents that while the recent media reports reflect a greater level of detail about the investigations, they do not contain any developments concerning Chetham's that we were not already aware of. We continue to offer the police our assistance with their inquiries.
"The trial and conviction of Michael Brewer, a former teacher at our school, and the subsequent police investigations raised serious and important issues. In terms of actions being taken by the school, whilst the recent inspection reports by Manchester Children's Services and the Independent Schools Inspectorate (ISI) found that our students felt safe and happy, they identified a number of weaknesses in our safeguarding processes and procedures.
"We are addressing these as a priority. Many of the changes have already been implemented and we are working with the Department for Education and Manchester Children's Services on this. A detailed Action Plan has now been submitted to the Department of Education for approval.
"Our responsibility, as a school, is to ensure that our young musicians have the facilities and resources that they need and can thrive in a safe and supportive environment. We are extremely proud of our school which we believe makes an invaluable contribution to the community and the musical life of the nation. However, the safety and happiness of our students is, and always must be, our top priority."
The Chetham's action plans includes the:
:: Introduction of a safeguarding sub-committee of the governing body tasked with oversight of all safeguarding at Chetham's
:: Appointment of experts to a safeguarding commission which will oversee and advise on all aspects of safeguarding
:: An annual independent audit of our safeguarding policies and procedures
:: Opportunities for additional parental engagement - a new "parents' extranet forum" and "parent governor" participation on the governing body.
The RNCM said it could not comment on the police investigation.