Two pet dogs have thwarted a sexual assault on a woman at a cemetery in Melbourne's west, fending off the man who attacked their owner.

Key points: The man approached the woman from behind and pushed her to the ground as she walked her dogs through the cemetery

The man approached the woman from behind and pushed her to the ground as she walked her dogs through the cemetery Her dogs attacked the man, who then ran off

Her dogs attacked the man, who then ran off Police are looking for her attacker and are urging anyone with information to contact Crime Stoppers

The woman was walking her dogs — RuPaul the shih tzu and Louie the terrier cross — in Williamstown cemetery as she did every night when she was approached from behind by a man at about 8:30pm on June 29.

"I'd stopped to do something and wait for my dog to come back from chasing a rabbit and I got pushed from behind into the ground," said the woman, known as Kate, which is not her real name.

"It really just came out of nowhere — I didn't hear anyone behind me or around me."

Kate screamed as the man held her in the mud and tried to pull her pants down.

"I started screaming pretty much straight away, like at the top of my lungs," she said.

Kate was in the habit of walking her dogs in the cemetery every night. ( ABC News )

Two-year-old Louie and one-year-old RuPaul then attacked the man, who ran off towards KC White Reserve on Park Crescent.

"They viciously attacked him — like growling, biting — and I think with my screaming and the struggling it made him stop," Kate said.

"It's amazing and I keep thinking about would have happened if they had run off or not … done anything."

"I think that they saved me.

"You wouldn't know, but they are extremely protective and will probably bite your ankles."

Kate ran home and called the police, who set up a crime scene at the cemetery and forensically examined the area.

Police have described RuPaul and Louie as "little heroes" for stopping the attack on their owner. ( ABC News )

She described the attack as "disgusting" and said she had stayed away from her home for a week after the attack because she was so shaken.

Detective Senior Constable Jenna Sladek of the Westgate sexual offences and child abuse investigation team joined Kate at a media conference today to appeal for public help to find her attacker.

"We know people congregate at the cemetery at night so we are keen to hear from anyone who witnessed the assault or may have been in the area at the time," Senior Constable Sladek said.

The man is described as having a large build and was wearing a black puffer jacket and white beanie at the time of the attack.

Senior Constable Sladek praised the two dogs for protecting their owner.

"We're classing them as little heroes," she said.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.