A US judge issued an emergency order early on Saturday blocking Elon Musk's government reform team from accessing personal and financial data stored at the Treasury Department, court documents showed.

US District Judge Paul A Engelmayer's order restricts giving access to Treasury Department payment systems and other data to "all political appointees, special government employees, and government employees detailed from an agency outside the Treasury Department."

The temporary restrictive order, which remains in effect until a February 14 hearing, also says any such person who has accessed data from the Treasury Department's records since Donald Trump was inaugurated as president on January 20 must "immediately destroy any and all copies of material downloaded."

Musk, the world's richest person, is leading Trump's federal cost-cutting efforts under the so-called Department of Government Efficiency (Doge).

The case was brought against Trump, the Department of the Treasury and Treasury Secretary Scott Bessent on Friday by attorneys general from 19 states.

The attorneys general alleged the administration violated the law by expanding access to sensitive Treasury Department data to staff from Musk's Doge.

Engelmayer's order said the states that sued would "face irreparable harm in the absence of injunctive relief."

"That is both because of the risk that the new policy presents of the disclosure of sensitive and confidential information and the heightened risk that the systems in question will be more vulnerable than before to hacking," he wrote.

Musk ran into controversy last week with reports he and his team were accessing sensitive data stored at the Treasury Department.

An internal assessment from the Treasury called the Doge team's access to federal payment systems "the single biggest insider threat the Bureau of the Fiscal Service has ever faced," US media reported. (AFP)