WASHINGTON (Reuters) - Former U.S. President Donald Trump's trade adviser Peter Navarro will be sentenced in Washington federal court on Thursday for refusing to cooperate with a congressional investigation into the Jan. 6, 2021 attack on the U.S. Capitol.

Federal prosecutors are seeking six months in prison for Navarro, writing in a court papers that he "chose allegiance to former President Donald Trump over the rule of law."

Navarro's lawyers are asking for probation, arguing the former White House adviser "reasonably believed" that he did not have to cooperate with Congress because he thought Trump had invoked the legal doctrine of executive privilege, which shields some presidential records and communications from disclosure.

Navarro was found guilty in September of two counts of contempt of Congress for defying a subpoena to turn over documents and provide testimony to the Democratic-led House of Representatives panel that investigated the Jan. 6 riot, along with broader attempts by Trump to overturn the 2020 election.

Navarro has asked that any sentence be put on hold while he pursues an appeal.

U.S. District Judge Amit Mehta, who has overseen the case, determined that Trump had not clearly directed Navarro to assert privilege. He was barred from making that argument to the jury during his trial.

Navarro, 74, advised Trump on trade issues during his presidency and served on a COVID-19 task force. He became a vocal supporter of Trump's false claims that his defeat to Democrat Joe Biden in 2020 was the result of widespread fraud.

The House Jan. 6 committee sought to interview Navarro about his plan dubbed the "Green Bay Sweep" to derail the certification of the election results in Congress.

Navarro is the second prominent Trump adviser to be convicted of contempt of Congress for spurning the House panel. Former Trump adviser and right-wing firebrand Steve Bannon was sentenced to four months in prison in 2022. He has avoided serving the sentence while he appeals his conviction.

(Reporting by Andrew Goudsward; Editing by Andy Sullivan and Bill Berkrot)

By Andrew Goudsward