Two people pretending to be Family and Community Services caseworkers went to a Queanbeyan family's home and claimed they were there to check on children.
The incident has prompted authorities to issue a warning and publish facefit images of the people.
NSW Police said a man and a woman went to the Karabar home and spoke to a mother who was home with two babies.
"The man and woman claimed to be FACS caseworkers and produced what appeared to be an identity card. They stated they were there to check on the welfare of the children," it said in a statement.
"The mother stated the children were asleep and told the pair she could call them to return when they woke, however the pair stated they would wait.
"A short time later the mother presented the children to the pair in the lounge room. After checking the children and their bedroom, the pair left the home."
The woman called Family and Community Services after becoming suspicious and discovered they were not from the authority.
"The visit was disturbing as the family have no known interaction with FACS or police," police said.
The man was described as Caucasian and in his 30s. He had a slim build with a fair complexion with short dark hair and a prominent nose. He was last seen wearing a business shirt and trousers.
The woman was also described as Caucasian and in her 20s, with a medium build and a tanned complexion. She had medium-length curly hair with a dyed streak and was last seen wearing an orange blazer with a dark-coloured skirt.