A man who threw a sandwich at a border agent in Washington DC has been charged with assault as tensions flare between protesters and law enforcement in the US capital.

The man, named by media as Sean Charles Dunn, was arrested after allegedly hurling a wrapped Subway sandwich at a Customs and Border Patrol (CBP) officer on Sunday.

Demonstrators have taken to the streets of Washington DC accusing Donald Trump of seeking to institute martial law after the president took federal control of the city’s police force and deployed 800 National Guard officers this week.

He has also flooded the streets with hundreds of federal agents from agencies including CBP, FBI and Drug Enforcement Agency (DEA).

Footage posted on social media shows the man later named as Mr Dunn standing face-to-face with officers, wearing a pink shirt and shorts with a wrapped sandwich in his hand.

He then throws the sandwich into the chest of an agent, before fleeing down the street as he is pursued by several officers. The footage does not capture his arrest.