The email arrived in inboxes shortly after Trump spoke at the Conservative Political Action Conference (Cpac). The messages came with the subject line “What did you do last week?” from a sender listed as HR.

The Office of Personnel Management (OPM), the federal government’s human resources agency, confirmed the email was authentic in a statement to CBS, the BBC’s US news partner.

“As part of the Trump administration’s commitment to an efficient and accountable federal workforce, OPM is asking employees to provide a brief summary of what they did last week by the end of Monday, CC’ing their manager,” it said. “Agencies will determine any next steps.”

In a copy of the email obtained by the BBC, employees were asked to explain their accomplishments from the past week in five bullet points – without disclosing classified information – before midnight on Monday.

The message did not mention whether a failure to respond would be considered a resignation.

The American Federation of Government Employees, the largest union representing federal employees, criticised the message as “cruel and disrespectful” and vowed to challenge any “unlawful terminations” of federal employees.

“Once again, Elon Musk and the Trump Administration have shown their utter disdain for federal employees and the critical services they provide to the American people,” Everett Kelley, union president, said in a statement.

On Sunday morning, Musk wrote on his social media platform X that “a large number of responses have been received already”, adding: “These are the people who should be considered for promotion.”

Newly-confirmed FBI director Kash Patel told his employees in an email that they should “pause any responses” to the OPM memo.

“FBI personnel may have received an email from OPM requesting information,” Patel wrote in a message obtained by CBS News. “The FBI, through the Office of the Director, is in charge of all of our review processes, and will conduct reviews in accordance with the FBI procedures.”

Earlier in the day, Trump touted cuts and told a crowd of supporters at Cpac that the work of federal employees had been inadequate because some of them work remotely at least some of the time.

“We’re removing all of the unnecessary, incompetent and corrupt bureaucrats from the federal workforce,” the president told the crowd at the annual conference in suburban Washington on Saturday afternoon.

“We want to make government smaller, more efficient,” he added. “We want to keep the best people, and we’re not going to keep the worst people.”

Elon Musk’s team has exacted wide-ranging changes to the US federal infrastructure through Doge and with approval from the White House.

Thousands of government employees at the Internal Revenue Service (IRS), the Pentagon and the Federal Aviation Administration (FAA), as well as other agencies, have been fired in recent weeks.

The email mirrors Musk’s handling of employees after he acquired social media platform Twitter, now called X, in 2022. As the staff there shrunk under his ownership, he issued ultimatums that included a now-infamous request to commit to being “extremely hardcore” at work or resign.

Trump has repeatedly applauded Musk’s government-cutting measures.

In a Truth Social post, Trump said that Musk is doing a “great job” in reducing the size of the federal government and that he would like to see him “get more aggressive” in the pursuit.