Caitlin Samuel, five, and her brother Aidan, who was three, were killed by their father, Perry Samuel, in November, 2006.

Samuel, who has a history of psychiatric problems, was jailed for life by a judge at Mold Crown Court after he admitted murdering the youngsters, described by their family as "little angels".

The children's mother, who was estranged from Samuel, was at a pop concert with friends in Manchester as her former partner murdered their children.

As well as the criminal investigation, the case prompted an inquiry into the actions of professionals in the region.

A serious case review was carried out by the Denbighshire Local Safeguarding Children board, with a view to establishing whether there were lessons to be learned from the case about the way in which local professionals and agencies work together to protect children.

It looked at what could be done better in future to prevent similar tragedies, and how organisations can work together to better safeguard the region's youngsters.

The report stresses that no professionals from any of the agencies involved were to be held to blame for the deaths of Caitlin and Aiden.

Denbighshire Social Services, North Wales Police, Denbighshire education service, Conwy and Denbighshire NHS Trust (including the adult mental health and social care partnership) and North Wales probation service all came under scrutiny.

The report found communication between mental health professionals, and those charged with protecting children, was good.

But it does stress that "the needs of children should be considered more by professionals working with adults who have a severe mental illness".

Because Perry Samuel did not express any thoughts about harming his children to his family, the report concludes it "seems unlikely" therefore that he would have said anything to professionals, which could have forewarned them and helped to prevent the murders.

The agencies involved issued a joint statement, which read: "This report concludes several months of work by all the agencies involved, which looked at every aspect of the case and whether anything could have been done to prevent this tragedy.

"We acknowledge the findings of the report, which clearly state that no professional individual was to blame for the deaths and that the deaths could not have been predicted or prevented.

"However, we also acknowledge that there are some lessons to be learned and we will continue to strengthen the relationship between all agencies, to enhance communication and strengthen procedures and policies."