US President-elect Donald Trump aims to make loyalist Kash Patel the next director of the Federal Bureau of Investigation, he said on Saturday, in a move that would involve replacing the agency's current leader.

Trump announced the former advisor and Pentagon official, who has been critical of the bureau and is known for his controversial views on a so-called government "deep state," as his choice for the post on his Truth Social network.

The FBI's current director, Christopher Wray, was appointed to a 10-year term in 2017, meaning he would either need to step down or be fired.

The FBI under Wray — whom Trump appointed — has investigated the incoming president, sparking Trump's ire.

"Kash is a brilliant lawyer, investigator, and 'America First' fighter who has spent his career exposing corruption, defending justice, and protecting the American people," Trump wrote on Truth Social.

A fierce defender of the incoming president, Patel supports the Republican hardliner notion of an anti-Trump "deep state" of allegedly biased government bureaucrats working to stifle Trump from behind the scenes, even having written a book on the subject.

A son of Indian immigrants, Patel served in several high-level posts during Trump's first term, including as a national security advisor and as chief of staff to the acting defense secretary.

"Kash did an incredible job during my first term," Trump said, adding that the nominee would work to "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."