Almost 1,700 mental health patients have been wrongly discharged from support services during the pandemic in north Wales.
Last week it emerged Betsi Cadwaladr health board advised people to seek new referrals once the pandemic had eased.
It had estimated that between 200 and 300 were affected, but the true figure is 1,694, according to a letter it has since sent to a Plaid Cymru politician.
The health board has apologised and said it was contacting the patients.
Last week, Simon Dean, the health board’s interim chief executive, told a Senedd committee discharging the patients was an “error that should not have occurred”.
He estimated then that between 200 and 300 people were affected but said his team was “working through the precise number”.
In a subsequent letter to Plaid Cymru health spokesman Rhun ap Iorwerth, a health board official has now confirmed 1,694 patients were wrongly discharged.
People across north Wales were affected, rather than just Flintshire-based patients as initially thought.
Mr ap Iorwerth said: “One patient being discharged before time is one patient too many.
“To now learn that 1,694 patients were discharged early, while they still needed support from mental health services, is deeply distressing.
“I welcome the assurance that all 1,694 patients will be contacted in the coming days to be reinstated to this vital service, but the question remains as to how such a decision could have happened right across the health board area, and how there could have been such widespread ‘misinterpretation’ of guidance.
“It should have been pretty clear that this would be unacceptable.
Mr Dean said the health board’s primary mental health care service was “receiving referrals as normal”.
“We will also be contacting all recently discharged patients to review the level of support they may need,” he said.
“I would like to say how sorry I am for any distress that may have been caused.”
The Welsh Government, which placed the health board into “special measures” five years ago, said mental health services were “essential” during the pandemic.
A spokesman added: “While the way they’re delivered might change because of the current restrictions, we expect health boards to maintain services.
“We are aware of correspondence discharging patients from local primary mental health services in north Wales during the pandemic.
“Although they were provided details for contacting crisis services, this is not in line with our guidance.
“The health board has assured us that all patients affected will be contacted by their local service.”