Dr Rowan Williams has responded to a new report on sex abuse in the Chichester Diocese and has apologised to those who have been abused as a result of failings by the Church.
Dr Williams set up an inquiry into child protection policies after abuses by East Sussex vicar Colin Pritchard and Brede parish priest Roy Cotton.
He appointed Bishop John Gladwin and Chancellor Rupert Bursell QC as commissaries to conduct the inquiry in the wake of child abuse scandals - the first such appointments for more than a century.
The Archbishop said the interim report confirmed that there had been "many and longstanding failures in implementing a robust and credible safeguarding policy in the Diocese of Chichester".
A review in May last year found serious failings among the senior clergy after Colin Pritchard and Roy Cotton were allowed to continue working despite being accused of serious child abuse offences.
Colin Pritchard was the vicar of St Barnabas in Bexhill-on-Sea, East Sussex, until 2007, despite having been first reported to police over sex offences 10 years earlier. He was later jailed for sexually abusing two young boys.
One of the boys had said he was also abused by Roy Cotton, who worked as a parish priest in Brede near Rye, but prosecutors decided there was not enough evidence to charge him before he died in September 2006.
The Archbishop said there had been much improvement in the last couple of years, but there remained areas of concern. He said the work of the commissaries would continue and they would be supervised by the Archbishop's office.
Dr Williams said guidelines laid down by the national Church and the agreed standards of best practice had not been consistently followed. He added that flaws in safeguarding practice had put children and others at risk.
The current Bishop of Chichester has also responded to the interim report.
Dr Williams said he encouraged anyone who had suffered abuse to come forward and their privacy and wishes would be respected. A special helpline has been set up in conjunction with the NSPCC on 0800 389 5344.