The worker, a man aged in his 30s, was working at a factory on Dohertys Road in Laverton North when the incident occurred.

Radio 3AW reported that the man was on a walkway above a machine when he slipped and fell about 7pm on Friday. Two other workers heard the man's cries for help and activated the emergency stop button.

It took emergency services about an hour to free the man, who was treated by paramedics during the rescue operation. It was reported the man's leg was broken in several places.

An Ambulance Victoria spokesman said the man was taken to the Alfred Hospital in a serious condition. Worksafe are investigating the incident.