Police have released security vision of a man they want to question over a brutal sex attack in a laneway in North Melbourne, two kilometres from the CBD.

The victim was stalked, then bashed and dragged into the laneway and raped in the early hours of Sunday morning.

Officers have been looking at CCTV footage from premises along the one-kilometre route.

The footage - taken from a restaurant on the corner of King and La Trobe Streets - shows a man walking down the laneway just before the assault took place.

Police have also revealed the 23-year-old victim is a new mother who had been out celebrating for the first time since she gave birth two months ago.

The head of the Sexual Crimes Squad, Inspector Paul Binyon, says the bashing was severe and brutal, and she is lucky to still be alive.

"We are fortunate she is still here with us," he said.

"All things considered, she is lucky."

He says the attack was interrupted by passers-by, who heard the woman's cries for help.

"We have a young woman dragged into a public laneway [and] she was severely beaten," Inspector Binyon said.

"If not for the intervention from other people, who knows what the consequences could have been.

"There was certainly some quick actions from some passers-by and neighbours, and I think we should all be appreciative of those people."

'Pulling out all stops'

Inspector Binyon says assaults of such a brazen nature are rare.

"We're going to be pulling out all stops to find this offender," he said.

"My detectives are champing at the bit - they really want to catch this person and lock him up.

"We think this footage will give us a really good head start. We're confident this could be a strong link that puts the final link in the puzzle and helps us solve the crime."

Police have been doorknocking the area and say they have received valuable information from residents living nearby.

They have also pored through dozens of other security tapes in their search for more clues.

Police hope the public can help identify the man seen in the security vision.

They describe him as aged in his 20s with short dark hair, an unshaven face and about 175 centimetres tall.

Two views of a handbag similar to one stolen during a sexual assault in a laneway in North Melbourne on June 30, 2013. ( Supplied: Victoria Police )

"The public have been very helpful to this point but we are really looking for that final piece in the puzzle and we think this image will give us a good identification of this male," Inspector Binyon said.

"We think it's a good quality image and we're very confident that someone knows this person, they will be able to identify him readily from the image, from the detail in the image, and we would ask anyone who knows that person to contact CrimeStoppers."

Police say they are also searching for the victim's handbag.

Inspector Binyon says the victim has been released from hospital after having surgery for significant head and facial injuries.

"She has had plastic surgery to correct a deep laceration to her face," he said.

He says the victim has been receiving counselling, and has been reunited with her family who have flown from interstate.

Anyone with information can contact CrimeStoppers on 1800 333 000.