Patients are suing Dr Arackal Manu Nair, who it is alleged gave prostate cancer treatment to patients who did not have the disease.
Heartlands NHS Hospital in Birmingham and the Spire Parkway private hospital in Solihull, where Dr Nair practised, have recalled the affected patients.
The General Medical Council said it was investigating.
About 170 men who had their prostate removed have been contacted, the Heart of England NHS Trust said.
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Dr Nair is also alleged to have given some patients laser treatment - a high intensity focused ultrasound (HIFU) - which was yet to be approved by the National Institute for Clinical Excellence (Nice).
The GMC put restrictions on the consultant urologist's work while the allegations are investigated. These restrictions include not working in private practice and all work being supervised.
Medical negligence lawyer, Adam Wright, said his firm has been contacted by 57 of Dr Nair's former patients.
Spire Parkway Hospital said Dr Nair had not worked there since 2014 and Heart of England NHS Foundation Trust, which manages Heartlands NHS Hospital, said he had been "excluded from the trust since April 2014".
He worked at Southport and Ormskirk Hospital NHS Trust between February and July as a locum surgeon. The trust said he declared the GMC's restrictions imposed on him and he "gave [them] no cause for concern".
Legal action is being taken against a surgeon who is accused of carrying out unnecessary operations.