The author of the document said he discovered widespread incompetence throughout the service, including untrained staff taking blood samples, removing stitches, giving drugs and injections.
He said confusion between the medical and prison staff led to incorrect doses of drugs been given to inmates and courses of medication being stopped prematurely.
Among the jails to be criticised was Styal women's prison in
The Home Office commissioned report was produced by the department of training and staff development at the then Macclesfield Health Authority. A team of eight spent 1992 visiting 17 prisons and produced a 400-page report.
The Prison Service rejected the study, The Introduction of Competency Based Training For Hospital Officers, arguing that it went outside its remit. A Prison Service spokeswoman said yesterday that improvements had been made since the report and they were satisfied with the current standards.
But Tony Kilroy, former director of training and staff development at the health authority, now the East Cheshire NHS Trust Macclesfield, said the prison service was still in a shambles. 'Standards of practice were appalling.'
He added that recent changes to training of prison staff would change nothing. 'There is not the staff or expertise to bring about the improvements.'
The Prison Service commissioned a new report after Mr Kilroy's was rejected. It recommended setting up national qualifications for warders who became 'health care officers' in prisons.
David Blunkett, Labour's health spokesman, said: 'It is quite disgraceful if the Home Office has covered up a vital report of this nature. The Home Secretary must give a full explanation.'