Former Home Office Amber Rudd was failed by her officials during the row over immigration policy that led to her resignation as home secretary.
Ms Rudd resigned from the Cabinet after she “inadvertently misled” the Home Affairs Select Committee over targets for the removal of illegal immigrants.
But a report into the row found officials had repeatedly given her the wrong information and then failed to clear up the problem so that she could correct the record.
Ms Rudd said: "There are elements of this report which just show that, unfortunately, that area of the department did not have a grip on what was going on.
"I hope that there will be changes made as a result of this report so that people get a better service from Immigration Enforcement."
'Intended to embarrass me'
On BBC Radio 4's Today programme, she questioned why the report had been "sat on for nearly six months" and claimed she had been targeted by a series of leaks while she was home secretary.
"There were a series of leaks during the past year at quite a high level that were definitely intended to embarrass me," she said.
The report could clear the way for Theresa May to promote the Hastings and Rye MP back into the Cabinet - Ms Rudd said it was now "up to the Prime Minister" whether she returns to the front bench.
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The document, obtained by the Times, reveals she asked officials for advice on targets before her ill-fated appearance at the Home Affairs Committee in April at the height of the scandal over the treatment of the Windrush generation.
The report, written by Sir Alex Allan, the Prime Minister's independent adviser on ministerial standards, says "crossed wires" contributed to Ms Rudd's downfall.
She "was not supported as she should have been" by her officials before, during and after the committee appearance on April 25.
"In preparations immediately before the hearing, the home secretary asked 'Are there removals targets?' and was told 'No'. This led to her denial in the hearing," writes Sir Alex in an executive summary, the Times reported.
He adds: "I cannot establish how she was given this reply: the most likely explanation is crossed wires between her special adviser and her private office."
Ms Rudd told the Commons Home Affairs Committee that the Home Office did not have targets for removals.
The following day, however, she returned to the House to admit that Immigration Enforcement managers did use "local targets" and a memo later emerged referring to a target for enforced returns and progress towards a 10% increase "which we promised the Home Secretary earlier this year".