Almost 10,000 people have been offered a Covid booster jab in Wales despite not being eligible for one.
In a statement Health Minister Eluned Morgan said the mistake occurred due to the broader criteria for eligibility during the Spring booster campaign.
All of those incorrectly identified as eligible for the booster were listed as clinically extremely vulnerable.
The incorrect offers for a booster jab will be honoured, Ms Morgan confirmed.
In a statement Ms Morgan said the potential discrepancy between those deemed eligible and those turning up for the booster had been identified by health boards on 16 May.
After an investigation the Welsh government found that 9,500 people had been incorrectly included as being eligible for a spring booster - after a new measure was included within the Welsh Immunisation System (WIS), used to manage vaccinations.
"All those who have been incorrectly identified have been included in the clinically extremely vulnerable group of people who are eligible for antiviral and antibody treatment if they get Covid-19," she said.
"This error can be attributed to differences in the criteria for vaccination and treatment," Ms Morgan said.
"It is important to note that all these individuals are at high-risk of developing severe illness if they get Covid-19."
Under JCVI advice, only those aged 75 years and over, care home residents and individuals aged 12 years and over who are immunosuppressed should have been offered a booster.
Ms Morgan said she had decided to honour the offers due to "potential confusion and anxiety" which would be caused by withdrawing the offer at this stage.
However, she added that this decision "does not represent a decision to extend our programme beyond the eligibility criteria advised by the JCVI".
She added: "We have sufficient supply of vaccine in Wales to provide additional appointments and booster vaccines and we do not expect this decision to have any impact on eligibility for vaccination in the autumn."
"We will make sure all individuals affected are aware of the situation and we will apologise for the error."