Amber Rudd was failed by her officials during the row over immigration policy that led to her resignation as home secretary.
The senior Tory said an internal report into the events surrounding her resignation showed part of the Home Office “did not have a grip on what was going on”.
She quit the Cabinet in April after she “inadvertently misled” the Home Affairs Select Committee by saying there was no target for the removal of illegal immigrants.
But a report into the row found that officials failed to provide her with the correct information before, during and after the committee hearing.
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.”
“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.
The issue is politically sensitive because Mrs May was Ms Rudd’s predecessor at the Home Office.
A Downing Street spokeswoman told a Westminster briefing the report “raised some difficult and important issues”.
“The Home Office have rightly said they will learn from them and the Prime Minister will expect them to do that.”
The spokeswoman said the PM does not believe civil servants are acting against ministers.
She added that the investigation dealt with “a specific set of circumstances involving a small number of individuals” and “there is nothing to suggest such issues are widespread” across either the department or Civil Service.
Asked if the PM would like to see Ms Rudd back in government, the spokeswoman said: “That would be a decision for the Prime Minister in the future.”
The report by Sir Alex Allan, the Prime Minister’s independent adviser on ministerial standards, reveals that Ms Rudd 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.
“In preparations immediately before the hearing, the Home Secretary asked ‘Are there removals targets?’ and was told ‘No’,” Sir Alex said, which led to Ms Rudd’s firm denial at the committee.
The most likely explanation for the information given to Ms Rudd was “crossed wires between her special adviser and her private office”.
After Ms Rudd’s answer, as officials scrambled to establish the correct position there were “confused email exchanges” and she was never provided with a briefing that would have allowed her to correct the record.
“The home secretary was not, therefore, supported as she should have been during the hearing,” Sir Alex said.
His team were asked to produce “chapter and verse” on targets and their history but their note “left several questions unanswered”.
Ms Rudd “lost confidence” in the advice she was receiving and then took the “dangerous” decision to prepare for an urgent question in the Commons without officials present.
Sir Alex’s report did not recommend investigations into misconduct but said Mr Ind’s performance was “less than satisfactory” and the then Home Office second permanent secretary Patsy Wilkinson should have played a “more proactive role”.
Both officials have left the Home Office for other jobs in public service.