An employee at the US Department of Justice (DOJ) has been arrested for throwing a Subway sandwich at a federal agent deployed to Washington DC as part of President Donald Trump's vow to crackdown on crime.

Sean Charles Dunn, who had worked in the DOJ Criminal Division, was fired after video of the incident emerged. He is being charged with felony assault.

The presence of federal law enforcement agents, as well as the National Guard, has led to widespread anger in the mostly Democratic city.

Trump, a Republican, has said the deployment is necessary to fight crime and remove "drugged-out maniacs and homeless people". Local police data shows violent crime is at a 30-year low in Washington DC.

According to charging documents, Mr Dunn allegedly threw a "submarine-style sandwich" at a Customs and Border Patrol (CBP) officer on Sunday.