The US Supreme Court on Friday temporarily blocked a request from US President Donald Trump to allow him to fire the head of a whistleblower protection agency, weighing in on the president's executive actions for the first time since his inauguration. 

The decision, however, noted that the court could return to the demand next week, when a trial judge's temporary restraining order keeping the watchdog official in office was due to expire. 

"The application to vacate the order... is held in abeyance until February 26, when the TRO is set to expire," the unsigned Supreme Court decision said. 

The Trump administration had asked the Supreme Court to allow the president to fire Hampton Dellinger, who leads the Office of Special Counsel.

It was Trump's first appeal to the top court since returning to office and issuing a flurry of contested executive orders. 

The White House fired Dellinger, head of the Office of Special Counsel, on 7 February but the lawyer sued the president and a district court ordered he be reinstated.

The US Court of Appeals had rejected the Trump administration's request to overrule the decision.

The emergency appeal filed to the Supreme Court on Sunday branded this an "unprecedented assault on the separation of powers that warrants immediate relief." 

The Supreme Court, which includes three Trump-nominated justices, is primed to play a significant role in what some experts are suggesting is a looming constitutional crisis as the president tests the limits of his executive power. 

Trump, who began his second term last month, has launched a campaign led by one of his top donors, Elon Musk, to downsize or dismantle swaths of the US government.