Three of the new cases also involve female members of staff - who have all lost their jobs. The fourth case, currently under investigation, involves the husband of a woman staff member.
The four new allegations were all brought to the attention of Worcestershire CC social services by staff and parents. The social services report will be forwarded within three weeks to Mr Blunkett - along with details of the Renate Williams case and two earlier court cases in which the school has been linked with child sex abuse.
All of the alleged incidents are said to have occurred within the last four years. The scale of the scandal has led social services to investigate fears that a paedophile ring may have tried to establish connections in the school.
Worcestershire director of social services Peter Gilbert said: 'We will pass the report on to the DfEE for the secretary of state's attention as soon as possible. The school is privately run, so the local education authority does not have any control over it.
'I can assure parents that we will lift up every corner to see what we can unravel.' A spokesman for Mr Blunkett said: 'He has been keeping in touch with the court case and is naturally concerned about what is going on at this school.'