US first lady Melania Trump wants to oust the White House's deputy national security advisor, her office said on Tuesday, a stunning intervention amid reports of infighting in the administration.

"It is the position of the office of the first lady that she no longer deserves the honour of serving in this White House," Stephanie Grisham, a spokeswoman for the first lady, said in an email about the deputy, Mira Ricardel.

Ricardel, deputy to National Security Adviser John Bolton, was at a White House event with President Donald Trump just as the infighting was being reported.

US media reports had said Ricardel was likely to be fired soon, part of a wider shake-up in the high-turnover White House. Just last week, Trump fired his attorney general, Jeff Sessions, and installed a staunch loyalist in an acting capacity.

The fights in the White House are both about policies and personalities. Ricardel has reportedly been at odds with members of the Trump family, as well as Defence Secretary Jim Mattis.

There is also speculation about whether Homeland Security Secretary Kirstjen Nielsen and chief of staff John Kelly will keep their jobs.

CNN reported that Ricardel had clashed with the first lady's office regarding Melania Trump's recent trip to Africa. The flight's seating arrangements were apparently a source of controversy.