Australian Community Services Minister Lisa Neville has defiantly claimed she is "no quitter" as pressure increased for her to step down after revelations of multiple mistakes made by child protection services in a shocking abuse case.

In a shocking case revealed by the Herald Sun this Thursday, a man is accused of keeping his daughter a virtual prisoner, raping her almost daily for 30 years, starting when she was 11 years old.

Opposition leader Ted Baillieu slammed the minister for betraying Victorian's "sacred trust'' in her office and called for her to go.

The Brumby Government is reeling after a series of findings that have exposed major mistakes by the state's child protection services to look after the youngest and most vulnerable members of society.

An avalanche of questions in Parliament Thursday left Neville shaken but defiant that she would see through a reform of the state's welfare services.

She admitted to being "sickened'' by the allegations of incest and said Child Safety Commissioner Bernie Geary had begun an investigation into any contact arms of the state government ranging from the Department of Human Services to the police had with the family.

Premier John Brumby said he was shocked by the case, which he first learned of when he picked up this morning's Herald Sun.

Brumby said crimes against minors that occurred within a family were the worst possible crimes imaginable.

"I will get full advice and full reports from any relevant government departments that have been involved.

"Any crime against children, any crime against minors is appalling enough on its own, and then for any crime of this type to occur within a family, any crime of that type, speaking generally, is the worst possible crime you can imagine.

"Any crime that did occur in our state of this type would be met with the full force of the law.

"Speaking more generally if I could, any crime of this type is one that is shocking and is personally repulsive to me and to other Victorians."

He said the alleged crimes occurred under the watch of five or six state governments.

But Opposition sources believe the huge number of bungling in child services over recent months makes it impossible for Neville to continue.

DHS staff failed to conduct proper background checks on a known sexual predator before allowing a child into his care.

This comes only months after a two-year-old girl was bashed and killed after police and DHS staff failed to intervene despite being told the little girl had black eyes from a previous beating.

Child welfare advocates are demanding a full inquiry into the horror sex case, with claims authorities failed to investigate the alleged abuse despite being warned years ago.

All four children were born with health problems in major Melbourne hospitals. None have fathers listed on their birth certificates, raising concerns about why questions were not asked at the time. One of the children died from severe developmental problems soon after birth.

Sources close to the case have compared it to that of Josef Fritzl, the Austrian man who imprisoned his daughter and fathered seven children with her.

It could be "every bit as bad", a source told the Herald Sun. The woman and her three surviving children are in a safe house, being cared for by authorities.

Neville said today the case would be investigated.

Click here to read more on this story from The Herald Sun.