Washington DC - President Donald Trump fired the director of the National Portrait Gallery on Friday, claiming she was "highly partisan," as he pushes his plan to dismantle US cultural institutions.

The firing of Kim Sajet, whose publicly funded museum in Washington is home to paintings of key figures in American history, is the latest broadside against an arts world the Republican wants to tear down due to its perceived liberal leanings.

"Upon the request and recommendation of many people, I am herby (sic) terminating the employment of Kim Sajet as Director of the National Portrait Gallery," Trump wrote Truth Social.

"She is a highly partisan person, and a strong supporter of DEI, which is totally inappropriate for her position," he added, referring to policies meant to increase diversity, equity, and inclusion.

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The firing is the first concrete action Trump has taken against the Smithsonian Insitution since he issued an executive order promising to purge cultural bodies of "divisive narratives" and "anti-American ideology."

Sajet, who was born in Nigeria and raised in Australia, is a Dutch national, as well as a seasoned specialist in portraiture, who has led the National Portrait Gallery since 2013.

The Smithsonian Institution, founded nearly two centuries ago, is a Washington mainstay whose 21 museums are largely dedicated to US history and culture.

With free entry, they are a tourist favorite, sitting on the edges of the National Mall, a green esplanade that links the Capitol and the Lincoln Memorial, close to the White House.

Friday's firing follows the president seeking to remake the prestigious Kennedy Center by naming himself chair and reorganizing its board of directors.