Police in Scotland have arrested and charged nuns and a number of other former staff in an investigation into alleged child abuse at a Catholic children’s home.

The nuns are among 12 people who have been charged by detectives investigating detailed allegations of systematic physical and sexual abuse of children over many decades at Smyllum Park in Lanark.

Police Scotland said another four former staff at the Catholic institution would be reported to the Crown Office, Scotland’s prosecution service, later on Thursday.

The force would not release any further details about the identities of those charged or the offences they face, pending final decisions by prosecutors.

“Twelve people, 11 women and one man, ages ranging from 62 to 85 years, have been arrested and charged in connection with the non-recent abuse of children,” it said.

“All are subject of reports to [the] Crown Office and Procurator Fiscal. A further four individuals will be reported today. Inquiries are continuing, it would be inappropriate to comment further.”

The allegations of abuse at Smyllum Park, including unsubstantiated claims of “satanic” rituals at the home, have been at the centre of a long-running official public inquiry into child sexual abuse at children’s homes in Scotland.

The Scottish child abuse inquiry (SCAI) has been told by former residents that lay staff and nuns at the home, run by the Daughters of Charity of St Vincent de Paul until it closed in 1981, repeatedly beat and punched them, verbally abused and humiliated them for wetting beds and left them without food and that some male and female staff sexually abused the children in their care.

It is alleged that at least one child, a boy aged six, died as a result of a severe beating that prevented him from recovering from an infection some days later.

Gregor Rolfe, a lawyer for the Daughters of Charity, told the SCAI last year that one male former member of staff may have sexually abused children whom he took on holidays. Those allegations were reported to nuns but not passed to the police.

“The order is deeply troubled by each of these failings,” he told Lady Smith, the chair of the SCAI and a high court judge, in November. “As Daughters of Charity our values are totally against any form of abuse and thus we offer our most sincere and heartfelt apology to anyone who suffered any form of abuse in our care.”

The families of former residents were horrified to discover that the remains of up to 400 children were buried in a large plot of unmarked graves in a cemetery nearby.

More than 11,000 children were placed at Smyllum Park from its opening in 1864 to its eventual closure 117 years later. Some were orphaned, but others were from families unable to look after them. Death certificates revealed that many of the children died from tuberculosis, pneumonia and pleurisy.

Smith is expected to release a special preliminary report on Smyllum Park in coming weeks. Her full report is not expected until some time after October 2019.

The Scottish Daily Mail reported on Thursday that police had also begun a separate investigation into the Sisters of Nazareth, another Catholic order that ran children’s homes that are under scrutiny by Smith’s inquiry.