Health ministers were warned about Haringey council's child protection processes just months before the death of a baby at the centre of an abuse scandal.
The concerns were raised in a letter sent in February 2007 to the Department of Health claiming that Haringey's social services department was not following child protection procedures.
The letter was forwarded to the Department for Children, Schools and Families, which was then headed by Alan Johnson, who is now the health secretary.
The department suggested that the whistleblower should contact the Commission for Social Care Inspection.
Six months after the complaint was made, a baby, who cannot be named for legal reasons, died after more than 60 visits from health and social work professionals.
His mother, her boyfriend and a lodger are awaiting sentencing for causing or allowing his death.
It comes eight years after the Victoria Climbie tragedy, when a young girl living in Haringey died following prolonged abuse by her carers.
A DCSF spokeswoman confirmed that the department had received the letter and had referred its author to the Commission for Social Care Inspection.
She said: "The permanent secretary of the DCSF has looked at the reply and is confident that the proper procedures were followed."