Authorities on high alert across US as fears over far-right violence intensify

FBI says far-right extremist groups planning armed protests in all 50 state capitals as well as in Washington

US officials are strengthening security measures in Washington DC and across the country as the FBI said far-right groups - many using social media - were continuing to threaten plots before Joe Biden's inauguration as president on 21 January.

As the National Park Service closed the Washington Monument, and the grounds of the US Capitol - which were stormed by a mob of pro-Trump extremists last week - were closed to visitors, with some 10,000 national guard being deployed across DC, the FBI said far-right extremist groups were planning armed protests in all 50 state capitals and in Washington, DC.