A dig at an Adelaide factory site for any remains of the missing Beaumont children has been called off, South Australian police have confirmed.

Detective Chief Superintendent Des Bray told the media that nothing of interest to the investigation had been found and the latest search had been abandoned.

Police had previously investigated the New Castalloy site but mounted a fresh dig in another area after two brothers told police they had once dug a hole for owner Harry Phipps, a person of interest in the Beaumont investigation.

Experts, including an anthropologist, spent most of Friday at the factory site at North Plympton, but police said only "non-human bones" were found.

Sorry, this video has expired Police excavate site at New Castalloy factory

"I can confirm that we have found bones of various animals, possibly cows, horses and sheep, but there is nothing human that has been located," Superintendent Bray said.

He said police were confident there had been holes dug previously in the area they searched on Friday.

"Those holes have been used for at least a period of time as a tip or possibly for household refuse," he said.

"But there is nothing that has been located today that is in any way connected with the disappearance of the Beaumont children."

What became of the Beaumont children has been a mystery for more than half a century. ( Supplied: SA Police )

Superintendent Bray said the elderly parents of the three children would not be forgotten after the latest search effort.

"Sadly this means for the Beaumont family we still have no answers, we still have a lot of work to do," he said.

The factory site was once owned by Mr Phipps, an Adelaide businessman who died in 2004.

Superintendent Bray said recent days had also been a difficult time for the Phipps family.

Police said they found animal bones at the site. ( ABC News: Tony Hill )

He said police were still going through information they received in dozens of recent calls from the public.

"We haven't had a case with so many people nominated as a person of interest," he said.

"Some of those people are considered and discounted.

"There's probably a dozen or so people who we've had a more serious look at over time and some of those people are our most notorious and vile criminals."

The media used ladders to see the excavation work at the New Castalloy factory in North Plympton. ( ABC News: Chris Nilsen )

Superintendent Bray said the outcome of the latest search was disappointing but not unexpected.

"I don't think there's anybody in the country that doesn't want to find the Beaumont children," he said.

"I issued a warning at the start of this that we needed to temper expectations and that was for a reason.

"It's disappointing, it's not surprising, but we'll continue to work to find the Beaumont children."