US President Donald Trump has decided to sack National Security Advisor HR McMaster, in what would be the latest in a string of high-profile White House departures, The Washington Post reported Thursday.

The newspaper said that Trump is discussing potential replacements for McMaster, but is willing to take his time because he wants to avoid humiliating him as well as to have a successor ready.

White House spokeswoman Sarah Sanders said that there were no changes at the National Security Council, a response that avoided the issue of whether any were being planned.

"Just spoke to @POTUS and Gen HR McMaster - contrary to reports they have a good working relationship and there are no changes at the NSC," Sanders wrote on Twitter.

The Post said that some in the White House were hesitant to remove McMaster until he had "a promotion to four-star rank or other comfortable landing spot."

While Trump reportedly wants to avoid humiliating McMaster, that did not appear to have been a particularly high priority when he removed secretary of state Rex Tillerson two days ago, a move he announced on Twitter.

A top aide said Tillerson did not speak to the president before his firing was announced and was not given a reason for his dismissal.

Tillerson's sacking came less than two weeks after Trump's top economic advisor Gary Cohn quit in protest against the president's decision to levy tariffs on imported steel and aluminum.

The previous year saw the departure of Trump's first national security advisor Michael Flynn -- who lasted just 22 days in his post -- as well as chief strategist Steve Bannon, who made it seven months, and Reince Priebus, who stayed in his job for less than six.

Speculation is rife over who will be the next official to go.

Candidates include education secretary Betsy DeVos, who struggled in two recent TV interviews, housing and urban development secretary Ben Carson, who controversially spent over $30,000 on a dining room set, the Post said.