Child Youth and Family is backing claims of abuse by two boys, despite their caregivers being cleared of criminal charges.
A jury at Auckland District Court on Wednesday found Andrew Hemara, 53, and wife Jenny-Lee Hemara, 49, not guilty of of abusing boys in their care.
The couple had denied they had done anything wrong and the jury's verdict was unanimous on all 14 charges of assault and ill-treatment of three boys between 2004 and 2010.
However CYF said its own investigation into abuse was substantiated and the couple's caregiver status has been revoked.
Two of the three boys who made claims against the couple said they were repeatedly kicked, punched and were forced to sleep outside without blankets.
In a statement, Child Youth and Family spokesperson Sharon Thom said while the Hemaras were found not guilty of criminal charges, they breached the agency's policy.
"The Hemaras have not been caregivers for us since the allegations arose. While they were found not guilty of criminal charges in court, our own investigations into abuse were substantiated.
"The use of physical force as a means of disciplining is completely unacceptable and contrary to our policy regardless of how difficult and complex children's behaviour can be. The Hemaras knew this. That's why we have such robust processes in place to assess and approve caregivers.
"The Hemaras gave us no reason to believe they would be anything other than the loving, nurturing caregivers these children deserved. We set the bar very high in our expectation of how caregivers look after children and young people in our care.
"These children have already been through a lot, and we expect the people entrusted by us to care for them to do so in a safe and nurturing way. Sadly in this case, the Hemaras ignored our requirements, and let these children down, as a result, their caregiver status was revoked."
Ms Thom said it was immensely disappointing that the abuse happened to children and young people in its care. The focus was now to make sure the children and young people are okay after what had been a very tough few weeks for them.
After the verdict Andrew Hemara said the couple had not been treated fairly. "I don't think we really should have been there, everyone just goes by their (CYF's) policies. As soon as a young person jumps up and makes a noise, in our case they just should have been talking with us all the way, we shouldn't have been there."
However the Association for Social Workers, which represents some Child, Youth and Family staff, said it was backing the agency's stance.
Association's chief executive Lucy Sandford-Reed said while the couple were found not guilty and the abuse did not meet a criminal threshold, it does not absolve them of responsibility.
"If a parent is ill-treating their children or abusing them and whether we use Section 59 of the Crimes Act and the amendments to that, physical abuse is not acceptable as a method of parenting and Child, Youth and Family set a high standard for that around their foster parents. These people quite clearly breached that standard."
Ms Sandford-Reed said the couple's behaviour did not amount to good parenting.
But Family First national director Bob McCoskrie said the Hemara name had been dragged through the mud and yet there was no truth to the boys' allegations.
"CYF owes a huge apology to the Hemaras, it's ruined their lives, they've been slammed by CYF and they didn't get name suppression so they've been living under this shadow since 2011 and it seems like they were guilty until proven innocent and yet they were trying to help really difficult kids that were being referred to them by CYF.
"Family violence is such a hot political potato that the police are not doing appropriate investigations, using their judgement and using discretion. They're not doing their homework basically and they're putting these cases through to court and this isn't the first one that I've heard about where if the police had done a bit more homework we could have saved a whole lot of grief and got to the truth a lot quicker."
Mr McCoskrie said the police should have acted differently in dealing with the boys' allegations.
"They should have got character references, they should not have accepted at face value the word of some troubled kids. Sure you've got to believe serious accusations that are made but you at least check whether they are true or not and unfortunately it didn't happen until three yrs later when it finally got to court that they actually did this investigation and the jury said no, they're not guilty.
In a statement, police said any matters that police put before the court always have to reach a certain level of evidential sufficiency. The statement said police do not comment on the outcome of court decisions, so no further comment would be made.