Haringey Council was looking after Mary Stroman at the time of her death
The council at the centre of the Baby P and Victoria Climbie cases has been criticised in a report into the suicide of a 16-year-old girl in its care.
Haringey social services was supervising Mary Stroman because of her depression and self-harming. She took her own life in 2014.
The serious case review criticised the north London council for "avoidable delays" in taking "key action"
Haringey Council apologised for the mistakes which were made.
The review identified "very serious weaknesses" across the services which were meant to be protecting Mary.
An inquest last year heard the teenager had been sexually abused by an older man or men near to where she lived in north London.
At the time of her death, Mary had been told she would have to leave a residential school she was attending in Wiltshire.
Tumblewood Community School in Westbury is a school for girls with emotional and behavioural difficulties.
The serious case review, commissioned by the independent Haringey Local Safeguarding Board, investigated three local authorities in London and one outside London, four local safeguarding children's board areas, two police forces and 13 NHS organisations, as well as three independent care providers.
It offered some criticism of Tumblewood Community School, of the Islington Clinical Commissioning Group, and a school which she attended in 2011.
The review described the Met Police's response to Mary's claims of sexual abuse as "inadequate".
'Long delay'
It singled out Haringey Council for particular criticism over its failure to secure another care placement for Mary after recommending she leave the Tumblewood school.
This, the report said, was "clearly a significant, avoidable delay in taking a key action... which probably had the best chance of achieving enduring, positive change".
Mary's parents, Scott and Sue Stroman, welcomed the findings.
But they said: "Similar to the long delay in preparing today's review, Haringey took far too long to arrange care for our daughter."
A spokeswoman for Haringey Council said: "We accept the findings of the review and recognise that at times during this very complex case some mistakes were made, for which we apologise."
