US President-elect Donald Trump says he intends to appoint his former aide Kash Patel as the next director of the Federal Bureau of Investigation, or FBI.

Patel is a passionate supporter of Trump and an advocate for restructuring the FBI. His previous roles include serving as a senior official at the Department of Defense in Trump's first administration.

Christopher Wray, the current FBI director, was appointed by Trump to serve a 10-year term in 2017. Trump would apparently dismiss Wray or ask him to resign after he returns to the presidency.

Patel has been critical of the FBI's investigations into Trump, and has proposed closing down the bureau's headquarters in Washington and reopening it as a museum.

US media reports say Patel has called for a "comprehensive housecleaning" of government workers who are disloyal to Trump.

Trump said in a statement on Saturday that Patel will help the FBI "end the growing crime epidemic in America, dismantle the migrant criminal gangs, and stop the evil scourge of human and drug trafficking" across the border.