A public inquiry has been ordered in relation to serious concerns about the clinical practice of a hospital consultant in Northern Ireland.
Urologist Dr Aidan O'Brien retired from the Southern Health Trust earlier this year.
The trust notified the Department of Health of concerns on 31 July.
Health Minister Robin Swann told the Stormont Assembly that, to date, 1,159 patients' records have initially been reviewed and 271 patients or families have been contacted by the trust.
He said nine cases have so far been identified that meet the threshold for a serious adverse incident (SAI) review, while a further six cases are being reviewed in more detail to establish if those patients have come to harm.
Mr Swann said the concerns about clinical practice of the consultant urologist are "of the gravest concern".
"As Health Minister I want to firstly unreservedly apologise to these patients and their families for any upset and distress this has caused," he said.
"I would also wish to reassure them that I will endeavour to ensure that they obtain appropriate treatment, support and the care they need over the coming weeks and months."
Mr Swann added: "This emerging situation within the Southern Trust causes me and my department the gravest of concerns.
"While I remain convinced that the experience of patients who use our health services is overwhelmingly that of a safe and quality service, these incidents regrettably dent the confidence of service users.
"I fully acknowledge this and I will do all that I can to ensure that lessons are learnt, to prevent situations such as these occurring again."
The minister also announced an independent inquiry panel will be set up in relation to the recall of neurology patients in the Belfast Trust.
He said this is to enable the inquiry panel team to complete its work with "unfettered access to all relevant information", he stated.
Mr Swann said those involved in investigating will look "as far back as is necessary".
"In regards to the outworkings of this inquiry in regards to Mr O'Brien, that will be for the outworkings of the Royal College and also the inquiry itself, it's not for me to pre-determine that," he said.
Health committee chair Colm Gildernew responded to Mr Swann's statement, describing it as "very concerning".
"I welcome the fact that a public inquiry has been called into this issue," he said.