Having received the apology, Green Party MP Jan Logie questioned if the "circling interest'' of the British company and a decision not to fund the child advocacy service revealed a privatisation agenda.
That was strongly denied by Ms Tolley, who told Ms Logie to remove her tin hat.
"If the member reads the report that I released today [on CYF's future], no decisions have been made about what to fund and what not to fund. So stop looking for secret agendas.''
Corrections took control of Mt Eden prison from Serco in July after allegations of serious violence there.
Despite that rolling controversy, Ms Tolley has said she would still be open to Serco - which is looking at running child services in the UK - being contracted to provide more social services.
In question time today Ms Tolley was asked by Ms Logie whether she stood by an answer to a written question, which stated that she was not aware of such a visit having ever occurred.
The minister said that her previous answer had been based on wrong information provided by the Ministry of Social Development, and she apologised.
This morning MSD advised her that case managers from the Serco-run South Auckland Correctional Facility had visited the youth justice residence Korowai Manaaki.
"I have also been made aware that case managers from the Serco-managed site visited other CYFs sites to discuss the relationship between the prison and CYF, and/or the transition and management of young people from youth justice into adult corrections systems,'' Ms Tolley said.
"I make the point that Korowai Manaaki and South Auckland Correctional Facility are next door to each other.''
Ms Tolley said she was disappointed that she received incorrect information, but was pleased the case managers had visited CYF sites.
"The management of young people from youth justice into the prison system, it is absolutely essentialthat there was a good relationship to manage that transition.''
