22 Yr Old Aussie man repeatedly assaults a 10 month old on a train with a safety pin, tried to pierce ear

A man accused of repeatedly pricking a baby boy with a safety pin and hitting him in the head with a phone while on a train north of Sydney was on parole for several assaults, a court has heard.

Police said the 22-year-old man Brendon Duncan "cannot restrain himself" when requesting bail be denied for the alleged abuse that went on for over an hour against the 10-month-old baby.

The man was charged with domestic violence-related assault occasioning actual bodily harm and one count of common assault after was arrested at Woy Woy Railway Station Wednesday night after a passenger alerted police.

Keeping her identity hidden, the witness told 7 News what she saw was "evil, just pure evil".

"When the baby wouldn't take the bottle the male then tried to punch the child," she said.

Onlookers were petrified with fear, and too afraid to intervene they called the police.

Mr Duncan fronted Woy Woy Local Court where it emerged he was released on parole in March having served 10 months for six assault charges, News Corp reports.