NHS officials said the locum was employed at three hospital trusts between June 2010 and February 2015.
These were Nottingham University Hospitals NHS Trust, Chesterfield Royal Hospital NHS Foundation Trust and Royal Cornwall Hospitals NHS Trust.
While emphasising the risk is low, letters offering testing have been sent to the patients identified.
The largest number of affected patients is 223 in Nottingham. There were 120 at Chesterfield and 57 in Cornwall.
Dr Stephen Fowlie, Medical Director in Nottingham, said: "Transmission of the virus between an infected healthcare worker and a patient with an open wound can only occur if health workers themselves have an injury with bleeding when they are delivering patient care.
"There is no evidence this happened to this doctor in any patient contact."
He added that as well as clinic appointments, patients will be offered test results within 24 hours and support and advice from specialists for them and their families.
Officials emphasised HIV could not be passed on by day-to-day contact and while HIV positive staff can work on patients, there were strict conditions in place.
The NHS said it would not name the doctor involved but confirmed they were no longer working for the NHS.
After being referred to the GMC, the doctor had conditions placed on their registration but was suspended earlier this year. An investigation into their actions is under way.
An appeal has gone out to retest 400 patients treated by a doctor who was later diagnosed with HIV.