Excavation of an Adelaide industrial site, which could be the resting place of the Beaumont children, will be carried out on Friday, police have confirmed.

A range of experts will be involved in the dig at the New Castalloy site at North Plympton, which will begin about 8:00am.

The site was formerly owned by Adelaide businessman Harry Phipps, who died in 2004 but is still considered a person of interest in the case.

Police said a forward command post will be established on the property, with digging to occur at the site of a small anomaly identified by experts.

An anthropologist from SA Forensic Services will be on site, along with police from Major Crime and Forensic Response, a member of the SES and an expert from Flinders University.

The Beaumont children — Jane, 9, Arnna, 7, and Grant, 4 — disappeared from Glenelg Beach on January 26, 1966.

There have been 46 new reports about the case to Crime Stoppers in the nine days since police revealed they were preparing to carry out a new search.

A radar search of the factory site was carried out in 2013. ( SA Police )

The North Plympton site has been investigated before, but became a renewed focus of police efforts in recent months.

Recent geophysical testing uncovered the anomaly at the spot where two brothers said they dug a hole for Mr Phipps the same year the Beaumonts disappeared.

The area of interest is about 6 square metres in area and about 2.5 to 3 metres deep.

A sketch of the man witnesses said they saw with the Beaumont children the day they disappeared. ( Supplied: SA Police )

Police say the brothers were only boys at the time they dug the hole, and the new spot was about 50 metres away from where police have previously focused.

"We've searched in the areas they've nominated before but for a number of reasons they now believe it's further along," Superintendent Des Bray said last week.

But police have spoken of the need to "temper expectations".

"There's never been anything to prove that the Beaumont children are in the hole," Superintendent Bray said.

"[The brothers] are not suggesting it was a grave, but certainly it was sufficient to merit further investigation and that's what we've committed to do."

Former SA Police detective Bill Hayes described the new information that prompted police to search the site as the "best lead there has ever been in the case".

At the time the children went missing, several witnesses told police they had seen them with a tall, tanned, thin-faced man with short blond hair.

Sorry, this video has expired The new lead for Beaumont children case ( Angelique Donnellan )

A $1 million reward remains on offer by the State Government and police for information about the children's disappearance.

Anyone who has any information relating to the Beaumont case is urged to come forward.