Elon Musk, the billionaire head of the Trump administration's Department of Government Efficiency, threatened on Saturday to fire any federal worker who fails to explain what work they have accomplished during the previous week.

The threat, issued in a post on Musk's social media site X, was made just hours after U.S. President Donald Trump posted on his own social media network Truth Social that DOGE should get more aggressive in its attempts to downsize and reshape the federal workforce.

"All federal employees will shortly receive an email requesting to understand what they got done last week," Musk posted on X, formerly Twitter. "Failure to respond will be taken as a resignation."

As of Saturday evening, emails were sent to employees at federal agencies, including the Consumer Financial Protection Bureau, the National Oceanic and Atmospheric Administration and the Centers for Disease Control and Prevention, with the subject line "What did you do last week?"

The email, seen by Reuters, asks employees to reply to the email they have received with five bullet points summarizing "what you accomplished at work last week" and copy their managers.

The email gives employees until 11:59 p.m. ET on Monday to respond.

It is unclear what legal basis Musk has to terminate federal workers if they fail to respond to his request, which comes amid the Trump administration's fast-paced and controversial process to reduce government spending by shrinking the federal workforce.

The process, led by Musk and his young aides at the cost-cutting DOGE, has led to haphazard firings that resulted in numerous mistakes and forced several agencies to quickly rehire vital employees, such as those working on nuclear safety, defence and power generation.

The first wave of job cuts has targeted workers who are easier to fire, such as "probationary" employees on the job for less than two years or those who have started new roles within an agency.

The indiscriminate firings have led to DOGE terminating people whose jobs are not funded by taxpayers and have begun to anger people across the country who are concerned about a loss of services, as well as the impact of federal job losses on local economies.

Trump has repeatedly talked about Musk as the functional leader of DOGE, which is not a cabinet-level department, but the White House said in a court filing earlier this month that Musk had no authority over DOGE and was not an employee of the program.