Victim lays prostrate on ground following attack Picture: NSW Police Media

The man, who cannot be named to protect the identity of the child, left his nine-month-old son unrestrained in a pram near the stairs at Thirroul train station in December 2014, after he began arguing with his friend.

CCTV footage shows the man chasing after his mate and throw a series of punches at him, knocking him out onto the concrete.

PhotoSource:Supplied

Victim lays prostrate on ground following attack Picture: NSW Police MediaSource:Supplied

The father is then seen going back to his son, however he returns to his unconscious friend’s side when another man arrives.

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At one point he rolls the victim over and tries to wake him, at one stage taking the man’s wallet and going through it, all while the child remains alone at the other end of the station overpass.

Court documents said the father told police at the scene that his mate was “jumped” by “two young blokes”.

However the matter was reported to Family and Community Services and the father arrested a few days later and charged with assault and child neglect after police viewed the CCTV footage from the train station.

Fairfax Media reports that last Friday his lawyer Adam Barnes said his client had undergone alcohol rehabilitation and was remorseful.

He was jailed for eight months and fined $2000 but is free on bail while an appeal is lodged.