A homeowner has told of his disbelief after tradies unearthed human bones while doing plumbing work at a holiday home on Victoria’s Phillip Island.

Plumbers were installing a septic tank in the backyard of the Hazelwood Court home in Silverleaves when they unearthed a skull and vertabrae around 8.30am.

Homeowner Greg and his wife bought the property on the small island three years ago.

Homeowner’s ‘shock’ after tradies unearth human bones in backyard (9News)

“It’s our holiday home, and we love it. It’s a beautiful area, love it dearly,” he told 9News.

“It was pretty obvious what they’d found because, you know, we went into the backyard and saw what was going on.”

9News has been told the remains belong to an adult and may have been there for some time.

“To discover that someone’s lost their life here, in such a beautiful beach area, is really upsetting,” local resident Olympia said.

The state’s top detectives are now looking at whether the discovery could be linked to a high-profile cold case. (9News)

Forensic officers spent the day sifting through backyard soil on their hands and knees, while detectives from the homicide and missing persons squad went door-to-door searching for clues.

The state’s top detectives are now looking at whether the discovery could be linked to a high-profile cold case.

“You go through quite a range of emotions, from disbelief through to shock,” Greg said.

“I’m hopeful that it’s somebody’s very sad story, which will now come to closure.”

Plumbing works were being done on the home on Hazelwood Court in Silverleaves when the bones were discovered about 8.30am. (Jack Morgan/WIN NEWS)

The area where the remains were found is not within a known Indigenous burial site.

The remains will undergo forensic testing, which could take weeks or even months.