Peter Navarro, a former trade adviser to President Donald Trump, has been convicted of contempt of Congress for refusing to co-operate with a probe into the 2021 US Capitol riot.

Prosecutors said Navarro acted "above the law" by ignoring a subpoena from a congressional investigation.

He faces up to a year in prison for each of the two contempt counts.

Outside court, Navarro vowed to appeal against this "landmark case" all the way to the Supreme Court.

"This is the first time in the history of our republic," he said, "that a senior White House adviser, an alter ego of the president, has ever been charged with this alleged crime."

Navarro, a former senior trade adviser, was served a subpoena by a US House of Representatives select committee in February 2022.

But he did not hand over any emails or documents or appear to testify before the Democrat-led House panel.

The committee had hoped to question Navarro about efforts to delay certification of the 2020 election, according to a former staff director for the panel who testified in court.

Navarro was indicted in June 2022 and arrested by FBI agents at a Washington airport as he was boarding a flight to Nashville, Tennessee.

He was convicted by a 12-person jury on Thursday of two counts of contempt.

During a brief trial this week, prosecutors sought to portray the case as a relatively straightforward one with far-reaching implications.

"This case is all about a guy who didn't provide documents," justice department prosecutor John Crabb said in his opening statement.

"This case is just about a guy who didn't show up for his testimony. This case is that simple".

During their closing arguments, prosecutors said Navarro chose his allegiance to Mr Trump over complying with the subpoena.

"That is contempt. That is a crime," prosecutor Elizabeth Aloi told the court.

Navarro's lawyer, Stanley Woodward, argued that the evidence would "not show that Dr Navarro was wilful in his failure to comply".

When contacted by the committee, Navarro said former president Trump had instructed him to cite executive privilege.

This is a legal principle which allows certain White House communications to be kept under wraps.

But last week, Judge Amit Mehta, an Obama nominee, ruled there was no evidence that Mr Trump or executive privilege could have allowed him to ignore the committee's summons.

Navarro served as Mr Trump's senior trade adviser throughout his presidency, and was a member of the Covid-19 task force.

He has boasted about his part in a plan to overturn the election results on 6 January, 2021 - calling it the Green Bay Sweep - a reference to a tactic in American Football.

In addition to a maximum sentence of a year in prison for each count, Navarro also faces fines of up to $100,000 (£80,000).

Another key Trump ally, former strategist Steve Bannon, was convicted of two counts of contempt for defying the committee's legal summons in July 2022.

Bannon was sentenced to four months in jail, but has remained free while his defence team appeals the conviction.

Navarro's sentencing is scheduled for January.