Police in Jersey are to continue searching underground rooms below a former children's home at the centre of abuse allegations.
It follows what police called "significant" finds by forensic teams at Haut de la Garenne on Thursday.
Experts excavating bricked-up cellars at the site uncovered a set of shackles and a shallow bath, the BBC's Robert Hall said.
On Saturday a child's skull was discovered on the premises.
Search teams have also been digging turf around the home's grounds which they believe may have been disturbed.
Some 160 people have said they were abused at Haut de la Garenne.
The BBC's Robert Hall said he had learned the shackles in the cellar had been found on the floor but may once have been fastened to the wall.
Mr Harper said the two discoveries in the cellar on Thursday were "items which witnesses have said were in there when offences were committed against them".
He added that the finds were made in a bricked-up cellar - one of three underground rooms being investigated by officers at the home.
The two items discovered would "tend to provide corroboration for some of the allegations which we have received about offences that were committed," he added.
However, he declined to answer questions about what the discoveries may have been, and refused to be drawn on reports that one of the items found was a set of shackles.
No further human remains had been found, he added.
Mr Harper said one of the items was discovered on February 27 and the second on February 28.
He added that detectives did not have a "definitive" list of missing children.
"What we do have are anecdotal statements along the lines of: 'We were in there with such and such a person,' and maybe a first name, 'and they got into a row and there were screams one night and they didn't appear again the next day and someone said they had run away to the UK'," he said.
"We are looking for all sorts of evidence which would include, I would have to say, human remains."
A sniffer dog reacted "strongly" when it entered the room on Wednesday, according to officers.
A forensic archaeologist has been sifting through large piles of rubble and soil in the cellar.
Mr Harper said a second underground room adjoining the first had still to be searched. It is understood to be the same size as the first - about 12ft square and 8ft high - and also bricked up.
Police have said that they anticipate it will take at least a week to clear the first room before they can move onto the second.
A former member of staff at the home who contacted police about a third underground room - unconnected with the first two cellars - will be asked to help officers locate it.
The former employee added that the third cellar was not part of the main building and was used as a store room, a police spokesman said.
House parents' statement
Tony and Morag Jordan, of Kirriemuir, in Angus, Scotland, who worked as house parents at Haut de la Garenne from 1971 to 1984, have insisted they have "nothing to hide".
In a statement issued through their solicitors, the couple said they would help police with their inquiries.
The former Haute de la Garenne home care home and Jersey Sea Cadets are the main focus of an investigation into the sexual and physical abuse of boys and girls between the ages of 11 and 15 dating back over several decades.