A federal judge in the United States ruled Friday to reopen a case taken by President Donald Trump against the government over the alleged leaking of his tax returns.

The case by Trump against the Internal Revenue Service had resulted in a settlement which provided for a $1.8 billion "anti-weaponization fund". While the stated purpose of the fund was to provide redress for others claiming to be victims of government "lawfare", critics described it as a slush fund for supporters of the US president.

Sitting in Florida, US District Judge Kathleen Williams reopened the case in response to 35 former federal judges arguing the settlement raises "profound questions" about judicial integrity and possible manipulation of the legal process. Williams has ordered Trump's lawyers to address the allegations by June 12.

Earlier on Friday, another federal judge had temporarily blocked the Trump administration from using the $1.8 billion "anti-weaponization" fund while she considered a challenge to its legality and funding structure.

Sitting in Virginia, US District Judge Leonie Brinkema ordered officials to pause all steps to implement the fund, including transferring money or processing claims, to "ensure that no funds are irreversibly disbursed". She said "it is important that the status quo be maintained" and set a hearing for June 12 on whether to impose a longer-term freeze.

The lead plaintiffs challenging the fund in Virginia include a former federal prosecutor involved in cases related to the Jan 6, 2021 US Capitol riot, along with other groups and individuals who argue the fund lacks congressional authorization and could misuse taxpayer money.

The US Justice Department has not yet publicly responded to the latest court order.