Cardiff was criticised in 2003 for failing vulnerable children

But Graham Williams' annual report said standards had improved, with councils giving the service greater priority.

Cardiff and Blaenau Gwent councils' children's services departments had caused extreme concern but had shown distinct signs of improvement.

His report will be presented to the assembly health committee next week.

Some authorities should search their own souls in terms of their standards Graham Williams, chief inspector of social services

Cardiff council came under the spotlight in recent years after a social services inspectorate report said the most vulnerable children in the city were not being cared for properly.

Mr Williams wrote to Cardiff in 2003 to set out improvements that were needed.

On Thursday, Mr Williams said there was still some way to go for some Welsh councils.

"Some authorities should search their own souls in terms of their standards," he said.

"Some authorities are already achieving the standards we have set, others are working very hard to lay the foundations, but some are still struggling to obtain basic standards."

"We also need to ask whether enough attention is being given to families who are struggling to cope but who have yet to call in the social services... we need to target preventative measures in health and education to contain the demand."