All 50 US states on high alert for armed protests leading up to Joe Biden's inauguration

In the capital Washington DC, the National Guard troops have been brought in to deter any repeat of last week's deadly riots.

The FBI had earlier warned that pro-Trump supporters could possibly take armed marches in all 50 state capitols with the aim of disrupting the swearing-in ceremony.

In DC, authorities arrested an armed man on Friday as security was ramped up, BBC reported.

Capitol Police confirmed on Saturday that a Virginia man carrying a "non-government issued credential" was stopped and arrested at a security checkpoint with at least one gun and 509 rounds of ammunition.

The man Wesley Allen Beeler, who was later released told the Washington Post that he was carrying a firearm because he works for a private security firm and that he did not intend to bring the firearm into Washington DC.

The arrest comes as authorities bolster security in Washington, where many streets - some miles from the Capitol - have been blocked off with concrete barriers and metal fences.

The National Guards are working in collaboration with the DC police in keeping a strict vigil and also helping it in its day to day duties.

The National Mall, which is filled with thousands of people for inaugurations, has been shut to the general public this time at the request of the Secret Service.

Joe Biden's team had already asked Americans to avoid travelling to the nation's capital for the inauguration because of the COVID-19 pandemic.

Sunday is expected to be a particular focus for protests, after posts on several pro-Trump and far-right online networks called for armed demonstrations on that day.

However, some militia groups have told their followers not to attend, citing heavy security or claiming that the planned events are nothing but police traps.