President Joe Biden has said rioters who stormed the US Capitol on 6 January 2021 "held a dagger at the throat of America and American democracy".

In a televised speech marking the first anniversary of the events, Mr Biden said they came "in rage", and "in the service of one man".

He accused his predecessor Donald Trump of spreading "a web of lies" that led to the attack on the Congress building.

Investigators have so far arrested 725 suspects in connection with the riot.

"Those who stormed this Capitol and those who instigated this incidence, held a dagger at the throat of America and American democracy", Mr Biden said in Statuary Hall, a section of the Capitol complex that was breached by rioters.

"They came here in rage, not in the service of America, but rather, in the service of one man.

"The former president of the United States of America has created and spread a web of lies about the 2020 election... His bruised ego matters more to him than our democracy or our constitution", he added.

On 6 January 2021, Trump supporters stormed the building as Congress was meeting to certify Mr Biden's presidential election victory. Images of US lawmakers cowering from the mob in the gallery of the House of Representatives on that afternoon shocked the world.

Mr Trump had urged protesters at a rally outside the White House shortly beforehand to "peacefully" march on Congress, but he also encouraged them to "fight" and stirred up the crowd with unsubstantiated claims of mass voter fraud in the election he had just lost.

The former president released an angry statement hitting out at his successor shortly after Mr Biden's speech. In it, he accused Mr Biden of "failure" and repeated false claims about the election.

Several other events are planned by Democrats, who have control over the US Congress, to mark the one-year anniversary of the attack.

House Speaker Nancy Pelosi presided over a moment of silence on the chamber floor. Later, in a testimonial on the floor of Congress she praised police officers who defended lawmakers and other people who were sheltered inside as the riot raged.

"The insurrectionists targeted more than just the building. They targeted democracy itself," she said.

Some Republicans plan to skip the day's commemorative gatherings. The party's Senate leader, Mitch McConnell, is leading a delegation to the funeral of a former senator in Atlanta, Georgia.

Florida congressman Matt Gaetz and Georgia congresswoman Marjorie Taylor Greene - two provocative pro-Trump members of the House - will hold a news conference later in the afternoon. Republican Senator Lindsey Graham has already accused Mr Biden of "brazen politicisation" of the 6 January riot.

Last January, Joe Biden gave an inaugural address outside the US Capitol that focused on national healing and unity.

Now, standing in the centre of the building nearly a year later - after it has become clear that the nation is as divided as ever - Biden put unifying rhetoric aside and took dead aim at Donald Trump and his supporters.

In some of the sharpest words directed at his predecessor since the 2020 presidential campaign, Biden condemned Trump's continued efforts to question the legitimacy of that election.

Not only that, he blasted Republicans who continue to stand behind the former president and endorsed national efforts to enact election reform to counter what he said were Trump-backed attempts to undermine voting rights.

This is an election year in America, with control of the US Congress and several key states hanging in the balance.

Biden's rhetorical shift could represent a strategic shift, as well - a decision that the Democratic base can most effectively be rallied with anger, not hope.