NSW babysitter, 64 'abused' young girl

A Sydney man sexually assaulted a three-year-old girl and produced child pornography while babysitting her, police allege.

The 64-year-old, who'd been looking after the girl in Parramatta, was arrested on Thursday morning after an investigation described by police as "extensive".

Detectives seized phones, computers and electronic storage devices and charged the man with multiple counts of producing child exploitation material, assault with intent to have sexual intercourse with a child under 10 and indecent assault.

He is expected to appear in Parramatta Local Court on Friday.