Elon Musk's aides have taken control of the US Treasury Department's payments system -- which manages trillions of dollars of transactions each year -- sparking alarm among critics.
Musk, the world's richest person, is leading President Donald Trump's federal cost-cutting efforts under the so-called "Department of Government Efficiency" (DOGE).
"The corruption and waste is being rooted out in real-time," Musk posted Sunday on X, the platform he owns.
Later, replying to a post outlining alleged payments to Lutheran charities, Musk said DOGE was "rapidly shutting down these illegal payments."
The Treasury's closely guarded payments system handles the money flow of the US government, including $6 trillion annually for Social Security, Medicare, federal salaries, and other critical payments.
Musk's control of the payments system was approved by incoming Treasury Secretary Scott Bessent and was made possible when a career official was put on administrative leave on Friday after refusing to hand over access, The Washington Post first reported.
The official subsequently retired from the department, a source close to the matter told AFP.
Trump on Sunday praised Musk as "a big cost-cutter."
"Sometimes we won't agree with it and we'll not go where he wants to go. But I think he's doing a great job," he added.
News outlet Wired was first to report that Musk has placed young surrogates working for DOGE into key government positions, with his team gaining unprecedented access to the payment systems typically restricted to career employees.
The staff, reportedly aged between 19 and 24, were also placed at the federal Office of Personnel Management, the HR department for public workers that sent out an email last week offering most employees a chance to leave the government on immediate notice with about nine months' pay.
Democratic lawmakers have expressed deep concerns about political operators having access to the US government's money flow, pointing to possible systemic risks to the economy.
Elizabeth Warren, the top Democrat on the Senate Banking Committee, blasted the move in a letter to Bessent as "extraordinarily dangerous."
"I am alarmed that as one of your first acts as secretary, you appear to have handed over a highly sensitive system responsible for millions of Americans' private data -- and a key function of government -- to an unelected billionaire and an unknown number of his unqualified flunkies," wrote Warren.
She also said that sidelining experienced staff in this crucial corner of government "puts the country at greater risk of defaulting on our debt, which could trigger a global financial crisis."
On X, Musk predicted "Excitement guaranteed" in response to a post that said DOGE would uncover an "unprecedented amount of fraud and corruption in numerous government departments."
