Federico Klein, who also worked for Trump's 2016 campaign, was seen wearing a "Make America Great Again" hat amid the throng of people in a tunnel trying to force their way into the Capitol on January 6, the papers say.

Klein pushed his way toward the doors where, authorities say, "he physically and verbally engaged" with officers trying to keep the mob back.

Klein was seen on camera violently shoving a riot shield into an officer and inciting the crowd as it tried to storm past the police line, shouting, "We need fresh people, we need fresh people," according to the charging documents.

As the mob struggled with police in the tunnel, authorities allege Klein pushed a riot shield that had been stolen from an officer in between the Capitol doors, preventing police from closing them.

Eventually, an officer used chemical spray, forcing Klein to move somewhere else, officials say.

Klein was arrested on Thursday in Virginia and faces charges including obstructing Congress and assaulting officers using a dangerous weapon.

He was in custody on Friday and couldn't be reached for comment.

It was not immediately clear whether he had a lawyer who could comment on his behalf.

At least five people died as a result of the January 6 riots and roughly 300 people have been charged.

Klein became a staff assistant in the State Department shortly after Trump's inauguration in 2017, according to a financial disclosure report.

A Department of State diplomatic security special agent interviewed by an FBI agent said that Klein worked in the Office of Brazilian and Southern Cone Affairs, according to the court papers.

The bureau is responsible for managing US relations with Argentina, Brazil, Chile, Paraguay and Uruguay.

Australian Associated Press