The singer and television personality Mel B has said she is "heartbroken" by the Windrush scandal victims' fight for justice, as the Windrush commissioner urged ministers to commit to providing funding for legal support for those affected by the end of October.

In April, the Guardian revealed that the Home Office had refused to pay compensation in more than half the claims made by victims of the scandal, in which mainly Black Britons who came legally to postwar Britain were wrongly stripped of citizenship and settlement rights.

However, in a series of cases, claimants who were initially refused compensation have learned they are entitled to it, after legal advice. Research led by the University of Sussex found the average successful compensation claim rose from £11,400 to £83,200 after legal help, with oneman who was initially offered nothing securing £295,000.

Despite this, the UK government has refused to provide Windrush compensation claimants with funded independent legal support of the kind given to those affected by the Post Office and infected blood scandals.

Now, Mel B, the television presenter Alison Hammond and the former justice secretary David Lammy are among the public figures backing calls from the Windrush commissioner, Rev Clive Foster, to end the disparity.

In a letter seen by the Guardian, Foster urged the migration minister, Jo White, "to show government is serious about putting things right" by committing to funding legal support at the Windrush National Organisation conference in Birmingham on 30 October.

Mel B, whose father was born on the Caribbean island of Nevis, said she felt privileged to support "Windrush families" by backing Foster's call and co-signing his letter.

"People affected by the Windrush scandal have already been through so much," the former Spice Girl said. "I have met and talked to many of them and the stories they tell break my heart. Now they are facing the next step – a compensation process.

"This is a step forward, but it can be so difficult and anxiety-inducing to have to fill out endless forms and papers, especially for those living on their own. Funded legal support could make a real difference in helping people access the compensation and justice they deserve.

"My own grandparents were part of the Windrush generation. I owe them so much."

Foster, appointed as the Windrush commissioner in 2025, said under the current system "the Home Office is deciding claims for harm caused by its own policies".

He has made a formal recommendation to the Home Office that it funds independent legal advice for claimants before an official decision and again at review, in a scheme designed by victims and lawyers. His letter's signatories include victims, campaigners, lawyers, academics, faith leaders, parliamentarians and celebrities including Mel B.

In the letter, Foster said: "Some survivors have died waiting for compensation … In several claims, evidence that changed the outcome had been held by government departments or other organisations all along.

"The parliamentary and health service ombudsman has also found cases where people were wrongly told they were ineligible, or where evidence they sent in was ignored.

"The UN committee on the elimination of racial discrimination has raised concerns … and parliamentary committees and human rights organisations have called for funded legal support. Some 65,000 people have signed petitions asking for it, and people who campaigned over the Post Office, Grenfell and Hillsborough have backed the call."

Lammy added: "We owe it to those affected to make sure that justice works in practice, not simply on paper."

Last year ministers introduced the £1.5m Windrush compensation scheme advocacy support fund, which provides community-based help to navigate the Windrush compensation scheme, stopping short of formal state-funded legal representation.

A Home Office spokesperson said the fund had "significantly enhanced" support, adding: "The home secretary is determined to put right the appalling injustices caused by the Windrush scandal, making sure those affected receive justice and the compensation they rightly deserve.

"The [compensation] scheme has now paid over £132m across 4,177 claims, and in January major reforms to the scheme came into effect."