The Archbishop of Canterbury has apologised for the "pain and hurt" suffered by victims of clerical child abuse.
Justin Welby said the scandal was something the church could "never ignore".
He was responding to a new report that raises fears that child-abusing clergy could have slipped through the net.
The final report into the scandal-hit Diocese of Chichester said some victims may still not feel able to come forward.
The investigation was first ordered by Welby's predecessor, Rowan Williams.
It followed a series of scandals involving clergymen within the diocese which has led to several being arrested, charged and convicted for historic sex crimes against children.
The report's authors, Bishop John Gladwin and Chancellor Rupert Bursell QC, said the diocese has "moved forward a very long way" in recent months and has put in place "excellent" safeguarding practices.
The diocese is "committed" to preventing any further abuse occurring and to responding effectively to the ongoing trauma of victims that will last "very many years", the report says.
It adds that "hard lessons" have been learned as the authors described a "dysfunctionality" within the diocesan senior team which under new leadership has positively changed.
But the report adds: "We do not intend, however, to give the impression that there remains nothing further to do. Indeed, this is far from the case as the senior team recognises.
"We believe that it is inevitable that there will be other survivors of the known abusing clergy who have not felt able to come forward. We also recognise that there may still be abusers who are as yet unrecognised."
The findings of the report, published on Friday night, have prompted Welby to renew his apology to victims of clerical abuse.
He said: "I would like to express my heartfelt thanks to not only the commissaries for their care and concern in the course of carrying out this visitation, but also to the survivors of abuse who have been able to share their experiences.
"The hurt and damage that has been done to them is something the church can never ignore and I can only repeat what I have said before, that they should never have been let down by the people who ought to have been a source of trust and comfort and I want to apologise on behalf of the church for pain and hurt they have suffered."