Large numbers of people of non-Caribbean heritage may have been badly affected by the Windrush scandal but the Home Office has shown a “lack of curiosity” about the adverse impact of its legislation on them, according to a critical report by the National Audit Office.

The report, titled Handling of the Windrush Situation, found the Home Office was failing in its duty “to be proactive in identifying people affected”.

“The department is taking steps to put things right for the Caribbean community, but it has shown a surprising lack of urgency to identify other groups that may have been affected,” said Amyas Morse, the head of the NAO.

The NAO’s conclusions in the report are comprehensively negative. It criticises the Home Office for poor-quality data that wrongly classified people as illegal immigrants, the risky use of deportation targets, poor value for money offered by hostile environment policies, failure to respond to numerous warnings that the policies would hurt people living in the UK legally, and its refusal to widen the scope of its search for victims of its policies.

Targets for removing illegal immigrants, in place since 2004, may have increased the likelihood that people living legitimately in the UK were deported in error, the study found. In 2017-18 immigration enforcement expected to achieve 12,800 enforced removals – around 230 to 250 a week. “These targets would have influenced how enforcement staff carried out their work, in a way that may have increased the risk of wrongful removals,” the NAO said.

In creating a policy that had few checks and balances, the Home Office did not “adequately prioritise the protection of those who suffered distress and damage through being wrongly penalised, and to whom they owed a duty of care. Instead it operated a target-driven environment for its enforcement teams,” the report states.

The Home Office has narrowly focused on analysing the detention and deportation files of 11,800 people from 12 Caribbean countries to calculate how many involved people born before 1973, who might therefore have been granted indefinite leave to remain under immigration legislation implemented that year.

But there are no plans to review the detention and deportation files of around 160,000 Commonwealth nationals from non-Caribbean countries to see who may also have been wrongfully detained or removed. The Home Office has said it would be disproportionate to undertake this work, but the National Audit Office said it found that approach “surprising” given there was an “onus on the department to use its own data to identify people affected”.

The Home Office still does not know how many members of the Windrush generation have been wrongly affected. Officials are unlikely ever to establish how many Windrush people were incorrectly denied a job or a home to rent, because there is no data to record those decisions, the report indicates.

The Empire Windrush ship in 1954. Photograph: PA

The Home Office failed to protect the rights of the Windrush generation when it implemented its hostile environment policies, despite acknowledging in 2014 that there were about 500,000 settled migrants who would find it harder to prove their status and would be negatively affected by new requirements to prove eligibility for services, the report found.

“It is our view that there were warning signs from enough different sources, over a long enough period, to collectively indicate a potential problem that merited further investigation,” it states.

Poor-quality immigration data increased the risk of wrongful removals and detentions and of mistaken decisions to deny public services to the Windrush generation, the report says. The National Audit Office and the chief inspector of borders and immigration have repeatedly raised concerns about the quality of the data underpinning the Home Office’s immigration system.

A 2016 recommendation from the chief inspector of borders and immigration to cleanse the database of individuals who were wrongly flagged as being in the UK illegally was ignored. “The department declined to cleanse its database,” the report states.

The NAO recommends that the Home Office should review data to see how other Commonwealth nationals might have been negatively affected by its hostile environment policies.

It offers a withering conclusion on overall effectiveness of the government’s hostile environment policy, which has been rebranded as the compliant environment policy, but which remains largely unchanged.

“It is clear that the department’s implementation of the policy, now resulting in a belated and costly exercise in seeking information and paying compensation, to say nothing of the reputational damage involved, was not value for money,” the report states.

Meg Hillier, the chair of the public accounts committee, said: “The Home Office’s careless implementation of its compliant environment policy has had a distressing impact on those of the Windrush generation who have been unfairly treated. It is shocking that the Home Office is not proactively reviewing other Commonwealth nationals’ cases and has not yet established the full extent of the problems.”

A Home Office spokesperson said: “The home secretary has issued a profound apology to the Windrush generation for the experiences they have faced. Our taskforce has taken thousands of phone calls and helped over 2,400 people of any nationality prove their status in the UK.

“The majority of those helped by the taskforce are of Caribbean origin, but we have always been clear that it accepts applications under the Windrush scheme from people of any nationality who arrived in the UK before 31 December 1988 and are settled here.”

Officials said they had reached out to wider Commonwealth citizens through Hindu and Sikh organisations, as well as through local mosques, and stressed that assistance and compensation were not restricted to members of the Windrush generation.