Two men appeared in a Sydney court on Thursday charged over the case that has shocked even hardened police officers.

Child Abuse Squad commander Detective Acting Superintendent Peter Yeomans, whose officers led the investigation, said he was lost for words to describe how horrific the allegations were.

The two men, both aged 50, were arrested in Ivanhoe, Victoria on Tuesday and extradited to Sydney on Wednesday night.

Neither man appeared in Waverley Local Court on Thursday when their matter was briefly mentioned. 

The case was adjourned to Central Local Court on Tuesday.

One of the men fathered the little girl, who was born in 2014 and now lives with her mother in a small town in the Central West.

It's alleged the men travelled to the town on April 19, 2015 and looked after the baby girl for three hours while her mother was at a training course.

The men allegedly sexually abused the 10-month-old baby over those three hours and allegedly took photos of her that they later uploaded to their computers.

Police will allege that, in a Skype conversation two days later, the father's partner spoke to an associate and said: "Her mother was out for a while. We did not have enough time to do everything that we wanted to unfortunately."

Some of his other alleged comments were too disturbing to publish.

Victorian police searched the home of one of the associates in March this year and, after searching his computers, found material that prompted them to search the Ivanhoe home of the two 50-year-old men.

There they found terabytes of material on their computers, including images of the baby girl and Skype conversations.

The father has been charged with two counts of sexual intercourse with a person under 10 years and the production, possession and sharing of child pornography.

His Legal Aid lawyer said he will be represented by the Aboriginal Legal Service at his next appearance. 

The father's partner has been charged with sexual intercourse with a person under 10 years.

He was also charged with further child porn-related offences and use of a child under 14 years to make child abuse material.