New York's anti-terrorism boss called Thursday on the United States to introduce new domestic terrorism laws to cover threats posed by internal extremists like the rioters who stormed the Capitol.

"We don't have domestic terrorism laws that measure up to that level, as we do with foreign," John Miller, who oversees the NYPD's counterterrorism operations, told reporters.

He noted that the US has so far been wary of such a law, adding that the country needs to look at it again in light of the rioting by supporters of President Donald Trump that left five people dead.

There should not be "a laundry list of federal statutes that we have to kind of call through to figure out which one we can fit to an individual crime," Miller said.

"There should be an overarching statute that covers domestic terrorist organizations. And if nobody thought that was a good idea two weeks ago, they should probably be thinking about it again now," he added.

US laws currently allow prosecutors to charge anyone deemed to provide even the slightest amount of support to designated foreign terrorist organizations such as Al-Qaeda or the Islamic State group.

Americans can be prosecuted if they post on an online Islamic State Group forum, but not if they post on a forum for a neo-Nazi group located within the United States, even if it is about arming itself.

Analysts interviewed by AFP have stressed in recent days that the United States is less equiped to deal with the threat of violence from far-right groups than it is jihadists.

Some 70 people have been indicted on charges related to the riot on January 6, with federal prosecutors saying they expect hundreds more in the coming months.

Authorities fear further violence ahead of Joe Biden's inauguration as president on Wednesday. The center of Washington DC is under lockdown and more than 20,000 National Guards have been mobilised.