A review could be carried out into how social workers looking after children abused by an "utterly depraved" sex abuse ring missed the offending for so long.

Marie Black, 34, was jailed for life at Norwich Crown Court on Monday after being found guilty of of 23 offences including rape, conspiracy to rape and inciting a child to engage in sexual activity, following a trial earlier this year.

The charges related to five young children - two boys and three girls - over a 10-year period. It included "raffling" the children and transporting them to sex parties for abuse by others.

Michael Rogers, 46, from Romford, Essex, and Jason Adams, 44, from Norwich, were each jailed for 24 years after being convicted for their parts in the abuse.

Speaking after sentencing, Judge Nicholas Coleman raised concerns that the victims were being actively observed by Norfolk County Council's children's services department between 2002 and 2009 when much of the most serious abuse took place.

He added: "I am not going to ask for a report to be delivered to me but this case cries out for a serious case review to better understand what happened."

Earlier the judge described the case as "the most harrowing it has been my misfortune to try".

Addressing the trio, he said: "I and the jurors had to listen to the truly gruesome detail of what took place.

"Your conduct towards these children can only be described as utterly depraved - the children were subjected to sexual abuse of the worst kind.

"They were simply passed around like toys."

Michael Rosen, executive director of Norfolk children's services, welcomed the sentences and said the social workers involved had "never lost sight of those children".

However, he said the council would now discuss the possibility of a serious case review with the county's children's safeguarding board.

He added: "Their social worker deserves credit for working tirelessly to keep them safe and ensure that their voices were heard. Her determination and commitment, in extremely challenging circumstances, has helped the children to achieve justice today.

"Sexual abuse is a crime that too often remains hidden and unreported and I am hopeful that the unified response from all of the agencies involved in this case will encourage other victims to reach out for help.

"These children have shown tremendous courage in speaking out and should be praised and applauded for their bravery in seeking justice.

"We welcome the judge's comments that our social worker did her best for the children.

"We will discuss with the chair of the Norfolk Children's Safeguarding Board whether this case meets the threshold for a serious case review as suggested by the judge.

"In cases such as this it is always standard practice to review actions, both our own and our multi-agency partners."

A serious case review takes place after a child dies or is seriously injured and abuse or neglect is thought to be involved. It looks at lessons than can help prevent similar incidents from happening again.

The trial heard that Black was instrumental in abuse against the children in and around Norwich and London.

It included forcing the children to have sex with and in front of one another. On occasions children's toys, such as Barbie dolls, were used in the attacks, the trial heard.

The trio are said to have hidden behind a "veneer of respectability" as they invited other adults to parties where the children were abused and played card games to decide who would abuse which child.

Seven others stood trial but were cleared of all alleged sex offences.

Norfolk's chief constable Simon Bailey said: "Child sexual abuse is one of the police service's greatest challenges and this case exemplifies just how appalling and depraved that abuse can be.

"I welcome the sentences passed at Norwich Crown Court today, but would point out that even though the offenders are now serving significant custodial sentences their victims are going to have to live with the impact of their abuse for the rest of their lives."