Key US departments within the Trump administration have told staff not to comply with a Saturday email from Elon Musk's cost-cutting initiative asking what they accomplished in the past week.

The FBI, state department and Pentagon were among agencies that instructed employees not to answer the message. Other department heads advised staff to comply, while some told workers to wait for further guidance before responding.

Musk said failure to respond by Monday at midnight would be interpreted as the employee resigning. President Donald Trump has yet to comment on the email.

The conflicting guidance caused confusion for hundreds of thousands of government bureaucrats as Musk's Department of Government Efficiency (Doge) task force leads an outside effort to aggressively reduce government spending.

The message sent to millions of federal employees on Saturday evening came after Musk posted on his social media platform X that government staff would "shortly receive an email requesting to understand what they got done last week".

In a copy of the email obtained by the BBC, employees were asked to respond explaining their accomplishments from the past week in five bullet points - without disclosing classified information.

The Office of Personnel Management (OPM), the federal government's human resources agency, confirmed the email was authentic.

The message did not mention whether declining to comply could affect employment status, despite Musk's social media assertion that "failure to respond will be taken as a resignation".

Newly confirmed FBI Director Kash Patel told his staff in a separate email later on Saturday that they should "pause any responses."

"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."

The state department sent a similar message, saying leadership would respond on behalf of the agency.

"No employee is obligated to report their activities outside of their Department chain of command," an email from Tibor Nagy, acting undersecretary for management, said.

The Pentagon told its staff: "When and if required, the Department will coordinate responses to the email you have received from OPM."

The Department of Homeland Security and the Federal Emergency Management Agency gave their employees similar instructions, according to reports.

In a sign that the OPM email may have come as a surprise to many agencies, a senior figure at the Department of Justice wrote to staff on Saturday evening to say: "Media reports indicate the email was distributed to employees throughout the federal government."

The message added that "at this point, we have no reason to believe this message is spam or malicious".

Later on Saturday evening, a follow-up email was sent clarifying that the OPM message was "legitimate" and that "employees should be prepared to follow the instructions as requested".

The justice department message also came with a warning to staff: "Do not include any sensitive, confidential, or classified information in your response. Should you have any questions about the contents of your response please contact your supervisor.

"If we receive additional guidance or information, I will update all employees, as necessary."

Agencies such as the Department of Transportation, the Secret Service and the Cybersecurity and Infrastructure Agency also encouraged their staff to comply, reports said.

Other departments, including the National Security Agency, the Internal Revenue Service and the National Oceanic and Atmospheric Administration, requested that employees await further guidance.

OPM did not immediately respond to the BBC's inquiry about whether some staff might be exempt.

The American Federation of Government Employees, the largest union representing federal employees, criticised the message as "cruel and disrespectful" and threatened to sue.

It is unclear how the email affects any of the roughly three million federal workers who may not have had access their emails this weekend.

Other government employees, such as those at the Consumer Financial Protection Bureau, were placed on leave in the last month.

The message came hours after Trump praised Musk's work on social media, adding: "I would like to see him get more aggressive."

The Democratic ranking member on the House Committee on Oversight and Government Reform hit out at the directive in a letter to the OPM.

Congressman Gerry Connolly of Virginia wrote that the agency should "immediately clarify that federal employees' nonresponse to this ill-conceived, weekend email does not constitute resignation".

"This threat is illegal, reckless, and yet another example of the cruel and arbitrary chaos Mr Musk is inflicting on the people's government and its dedicated public servants."

Most Republican members of Congress have been defending Musk and his broader efforts.

Congressman Mike Lawler of New York told ABC on Sunday that Musk's efforts were a "comprehensive, forensic audit of every department and agency in the federal government".

But Senator John Curtis, a Republican representing Utah, criticised Musk's methods, even as said he supported the ultimate goal of Doge.

"If I could say one thing to Elon Musk, it's like, please put a dose of compassion in this. These are real people. These are real lives. These are mortgages," Curtis told CBS. (BBC)