The Windrush scandal was "foreseeable and avoidable" and victims were let down by "systemic operational failings" at the Home Office, according to a report.
The Government department demonstrated "institutional ignorance and thoughtlessness" towards the issue of race and the history of the Windrush generation but the actions did not satisfy all of the features of institutional racism, findings from a critical independent review said.
Author Wendy Williams told reporters: "Warning signs from both inside and outside the Home Office were apparent for a number of years, and even when stories began to emerge in 2017 in the media about high-profile injustices, I have concluded that the Home Office was still too slow to react.
"I talk about a culture of disbelief and carelessness when dealing with applications.
"This was born out of a conviction that the hostile environment policy would be effective, was effective, and should be pursued at all costs.
"I have also talked about a culture of ignorance and thoughtlessness when dealing with matters of race, the Windrush generation, their history and circumstances.
"The Windrush generation were let down by systemic operational failings by the Home Office."
Labour MP David Lammy said the report was a "brutal indictment of the Home Office, which shows it is wholly unfit for the society it is supposed to serve".
He added: "The Windrush scandal was not an innocent mistake, but a systemic pattern of appalling behaviour."
Windrush victim Michael Braithwaite, who lost his job for not having up-to-date papers after arriving from Barbados as a child in 1961 and living in the UK for more than 50 years, told the PA news agency that the findings of the review had come "too late" and claimed officials and politicians were "still not addressing what needs to be done" to rectify the mistakes.
The Windrush Lessons Learned Review was commissioned after people with a right to live in the UK were wrongfully detained or deported to the Caribbean.
It called for Home Office ministers to admit that serious harm was inflicted on people who are British and to provide an "unqualified apology" to those affected and the wider black African-Caribbean community.
Other recommendations include commissioning a full review and evaluation of the hostile environment policy and that the Home Office should establish an overarching strategic race advisory board.
Ms Williams said the Windrush group had been "trapped by the hostile environment policy net".
She added: "Those without documents were set, some would say, an impossible task.
"Others would say an unreasonably high standard of proof to prove their status.
"And when they couldn't, they were subject to the most appalling injustice and that included the things we have heard; losing jobs, losing homes, losing access to services like healthcare, and in extreme circumstances being removed, being locked up and as we heard in one case, dying."
The report "carefully considered" whether the concept of institutional racism outlined by Sir William Macpherson in the inquiry into the death of Stephen Lawrence was "directly relevant to describe what occurred".
The inquiry found that although the case for institutional racism was supported by a number of factors, the Home Office did not satisfy the definition in full.
It said: "I have not found, on the evidence that I have reviewed, that the organisational failings satisfy the Macpherson definition in full.
"Nevertheless, although the context for the Macpherson Inquiry was different to this lessons learned review, I have serious concerns that the factors I have set out in this section demonstrate an institutional ignorance and thoughtlessness towards the issue of race and the history of the Windrush generation."
— Home Office (@ukhomeoffice) March 19, 2020
Since the scandal emerged in 2018, more than 11,700 people have been given "some form of documentation", Home Secretary Priti Patel told the House of Commons on Thursday.
She said "on behalf of this and successive governments", she was "truly sorry" for the "pain, suffering and the misery" inflicted on the Windrush generation, adding that there was an "ongoing mission" to "right the wrongs" caused by the scandal.
Meanwhile Theresa May, who was the Conservative home secretary when the hostile environment policy was introduced and prime minister when the scandal emerged in 2018, told the Commons chamber: "I have given my own apology previously but I do so again today."
She said the Windrush generation were British, in the country legally, and "should not have been treated in this way".
The Home Office identified 164 people who had been deported or put in detention since 2002 amid the Windrush scandal, records said.
A compensation scheme with an estimated budget of at least £200 million has been set up.
But last month, campaigners hit out at the "paltry" number of people who have so far received payments and said the process was "slow and onerous".
A total of £62,198 was paid out up until the end of last year and shared between just 36 people, despite the department receiving more than 1,000 claims so far.