A watchdog claims a council-run appeal process for school admissions is among the worst it has investigated.
Blackburn with Darwen's appeals panel for Tauheedul Islam Girls High School was flawed and an unacceptable approach led to "serious faults", it said.
Local Government Ombudsman Anne Seex called it probably the worst instance of multiple maladministration in a school admissions appeal.
In a statement, the council said it had apologised and learnt lessons.
Parents of two children with failed appeals complained to the ombudsman about the way the panel dealt with their cases, the report said.
The school had appointed the council to organise and run the panel. It appointed a clerk with no experience and training and a chairperson with no experience of admission appeals.
Although the panel accepted that the popular faith school had proven that it had no capacity for extra children, it decided to give places to a further 30 children.
But the clerk's notes were so inadequate that ombudsman investigators had to interview people to piece together how the panel reached its decisions.
Mrs Seex concluded: "The way the panel conducted its decision making and the decisions that it made probably amounted to the worst instance of multiple maladministration in a school admission appeal investigated by the Ombudsman's office."
As soon as the school became aware of the ombudsman's concerns it arranged fresh hearings with a new independent appeal panel.
Of the 32 who appealed again, three were successful - including one of the parents who complained to the ombudsman.
In a statement, the council said: "We apologise for the mistakes made during the appeals process 15 months ago.
"Lessons were learnt and the council and school acted promptly to make the improvements recommended by the Local Government Ombudsman.
"The Ombudsman is satisfied with this and has recognised that the same mistakes have not been repeated during this year's appeals process."