The Home Office has admitted that people have been wrongly denied UK status after refusing to provide DNA evidence in a breach of its own policy.

Sajid Javid, the home secretary, said the government had illegally demanded DNA evidence in family visa cases, with at least seven people denied the right to stay in Britain because they refused to provide DNA samples to prove family ties.

He apologised to those affected, who included relatives of Gurkha soldiers, and announced that a new taskforce had been set up for anyone who believed they had been wrongly asked to provide DNA.

Politicians and campaigners described the revelation as “deeply troubling” and another sign that, following the Windrush scandal, there was an urgent need for ”root and branch reform” in the Home Office.

Speaking to the House of Commons on Thursday, Mr Javid said: “At the end of June we became aware of some immigration cases where the provision of DNA evidence had been made a requirement – and it was not simply a request.

“Such demands are unacceptable. Today, I want to take the opportunity to apologise to those affected by this practice.”

The home secretary said the majority of cases identified had been part of a 2016 operation aimed at addressing fraud.

He said seven cases in this operation were refused on suitability grounds solely for the failure to provide DNA evidence, and a further six were refused partly for that reason.

Fifty-one further cases have been identified as part of a 2013 scheme to allow relatives of Gurkha soldiers to settle in the UK, which wrongly stated that DNA evidence was required, Mr Javid said.

A third scheme assessed immigration applications from Afghan nationals working for the UK government on the basis of mandatory DNA testing. Mr Javid said no one from this cohort had been refused on these grounds.

He said his department would seek to reimburse any individual who has suffered financial loss as a result of the errors and was continuing to closely examine whether any other groups had been affected.

He also said he was taking action to correct the situation and had given “clear instructions” that officials should not seek DNA samples. The provision of DNA evidence must be entirely voluntary, he added.

Expanding on his apology, Mr Javid said: “It is not fair, and this should not have happened. No one should have faced a demand to provide DNA evidence and no one should have been penalised for not providing it.”

It comes after it emerged in July that a letter had been sent by the Home Office to an applicant’s solicitor stating that it was “imperative” they submit DNA evidence to confirm the paternity of their client’s child, despite the fact that the child already had a British passport.

The applicant's solicitor, Enny Choudhury, of the Joint Council for the Welfare of Immigrants (JCWI), said: “My client and her child were rendered destitute for 2.5 years as a direct result of the Home Office’s illegal practices.

"It is clear that countless others will have been subject to the same treatment and it is astonishing that ministers still do not have a grasp on the failings of the Home Office.

"We agree with the home secretary that there must be a review, but it must be fully independent of him and his Home Office. No one could have faith in its competence to properly investigate its own failings.”

Yvette Cooper, chair of the Home Affairs Committee, said: “Coming after Windrush, this shows something is going very wrong in the Home Office again.

“A new wider review must be independent and should examine oversight failure and impact of policies on culture of Home Office operations.”

Steve Valdez-Symonds, of Amnesty UK, said the Home Office had “once again been exposed as being a law unto itself”.

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He added: “The home secretary needs to face up to the fact that problems in his department are systemic, chronic and deep-rooted.

“Over several decades, successive governments have consistently encouraged policies and practice which disrespect the law and harm the people directly affected.

“This dysfunctional department cannot continue to be rewarded by being given more powers while vital safeguards, such as appeal rights and legal aid, are stripped away.