Images of Sydney cable attacker released

Detectives have released images of a man they believe choked a woman with a cable bike lock in the yard of a western Sydney unit block during a random attack.

The 27-year-old woman was followed in Ashfield on Wednesday night before a man wrapped the cable around her neck and pushed her to the ground.

A man and woman sitting in a parked car nearby heard her screams and rushed to intervene.

The man confronted the attacker who then punched him in the face before running off.

NSW Police on Friday released CCTV images of a man, aged in his late 20s to early 30s, with a slim build with long hair in a bun.

He is pictured wearing a high-vis orange shirt and dark pants while carrying a satchel.

The semi-conscious victim was taken to the Royal Prince Alfred Hospital and discharged later on Thursday night.

Police have said the "frightening" attack was random and are urging anyone with information to come forward or contact Crime Stoppers.