Children in care in England are forced to wait an average of 20 months to move in with adoptive parents, according to new figures.
Children's Minister Tim Loughton said the first-ever local authority scorecards were a "trigger for urgent, detailed discussions" to speed up the process. It is part of an action plan for adoption which includes proposals to reduce the length of the approval process for would-be adopters to six months.
Council leaders and children's services professionals condemned the scorecards and warned they have the potential to cause "unnecessary and avoidable concern in communities where there shouldn't be any".
The figures show that 80 local authorities met the interim thresholds of 21 months from entering care to adoption and matching a child to a family within seven months of a court order. But 72 councils did not meet one or both of these thresholds which will be lowered to 14 months and four months respectively within four years.
Children in care in Hackney, east London wait the longest in the country to move in with adoptive parents, at two years and nine months on average. Merton, south London has the second longest time, at two years and eight months, and Liverpool is third at two-and-a-half years.
Mr Loughton said: "Hundreds of children are being let down by unacceptable delays right across the country and throughout the adoption process. Every month a child waits to be placed there is less chance of finding a permanent, stable and loving home. This cannot go on.
"I make no apology for shining a light on the system to hold local areas to account. I have been clear that we won't hesitate to intervene where the worst delays are not tackled effectively."
But council leaders and children's services professionals said local authorities could not risk shifting their focus from the quality of placements to speed.
The Local Government Association, Association of Directors of Children's Services and the Society of Local Authority Chief Executives released a joint statement which said: "Councils are passionate about helping children and take their responsibilities towards those in their care extremely seriously.
"The adoption scorecards have the potential to cause unnecessary and avoidable concern in communities where there shouldn't be any, and may put prospective adopters off. Children waiting for adoption will not benefit from government struggling to get its act together."