Tarrio, 37, faces a maximum sentence of 180 days in jail for each of the two counts against him and a US$1,000 fine when he is sentenced in April.

He was arrested in January when he arrived in Washington two days before the Jan 6 riot at the US Capitol.

Tarrio was charged with possessing two high-capacity rifle magazines, and burning the Black Lives Matter banner during a demonstration weeks earlier by supporters of then-president Donald Trump.

Following his arrest, a federal judge ordered him to leave the city pending a court date in June.

Tarrio did not take part in the deadly US Capitol riot. The FBI has said his earlier arrest was an effort to preempt the events of Jan 6, where several other members of the Proud Boys were taken into custody.

Tarrio has led the Proud Boys in confrontations with Antifa, an amorphous and often violent leftist movement.

Reuters has reported that he worked extensively as an informant for federal and local law enforcement following a 2012 arrest. Tarrio denied working undercover or cooperating in cases against others.