A new Government bill paves the way for paedophiles to be put in charge of children, Labour education spokesman Trevor Mallard says.
But Education Minister Anne Tolley calls his accusations "hysterical".
She says the Education Amendment Bill (No 2) only gives some childcare centres the same status as Sunday School or Scouts.
The bill removes a requirement for police checks on employees at short-stay childcare centres in areas such as swimming pools and shopping malls.
Mr Mallard said that made it easier for sex offenders to be put in charge of children in enclosed environments.
"This bill is an early childhood education sex-abuser's charter, because it takes away, for the first time, the requirement for those people to have a police check," he told Parliament.
Labour originally supported the bill after Ms Tolley said the licenses would be required in short-stay centres, Mr Mallard said.
The party was now opposing the bill until an amendment was made, he said.
Mr Mallard is trying to get the support of minor parties including ACT to stop the bill's progress through Parliament.
"These checks take a couple of minutes. There's no reason they should not be required."
Mr Mallard said the bill made it a parent's responsibility to check the background of those taking care of their child.
"That's something I totally disagree with.
"Ninety nine per cent of parents would assume if they are paying in a proper organised crèche then the person would be police checked."
A spokesman for Education Minister Anne Tolley said she would not be responding to Mr Mallard's "offensive and increasingly hysterical" comments.
Her response to Parliament was that many organisations such as Sunday schools, Guides and Scouts were also exempt from the police check requirement.
Short-stay childcare centres were still covered by normal health and safety laws and required to ensure their employees do not harm others, she said.
"There are large numbers of situations where parents make the choice to leave their children where it is not required under law to have police checks."
Her advice from officials was that short-stay centres should not be required to conduct checks under the Education Act as they don't provide education, she said.