A unit believed to be occupied by squatters is being investigated as a place of interest in the alleged sexual assault of a Melbourne woman last year.

A 30-year-old woman from Reservoir in the city's north was dropped off near her house by a rideshare driver on December 4, before she lost consciousness before 2am.

When she woke up, she found herself inside a unit on Strathmerton Street, where she found a man allegedly sexually assaulting her. It is believed this happened between 2am and 4am.

It is not clear how she was moved from the nature strip to the unit, which police now believe is unoccupied and used by squatters.

She pushed the man off, walked home and called police.

Police have released a computer-generated image of a man who may be able to assist with the investigation.

The man is believed to be of Middle Eastern appearance, aged between 50 and 60-years-old, with dark hair, olive skin, a thin build, and clean-shaven.

Anyone who may be able to identify the man, or with any footage of the area at the time of the assault, is being urged to contact Crime Stoppers.