Biden says Americans must ensure Capitol attack 'never happens again'

US President Joe Biden has said that Americans must ensure such an attack like that on the US Capitol a year ago "never happens again" as the country seems more divided than ever.

"One year ago today in this sacred place, democracy was attacked, simply attacked. The will of the people was under assault. The Constitution, our constitution faced the gravest of threats," Xinhua news agency quoted Biden as saying in a speech from Statuary Hall just outside the House chamber to mark the anniversary of the January 6 attack on the Capitol.

"I believe the power of the presidency and the purpose is to unite this nation, not divide it. To lift us up, not tear us apart," Biden said, accusing former President Donald Trump of spreading a "web of lies" about the 2020 election, which laid the groundwork for the attack on the Capitol a year ago.

"For the first time in our history, a president had not just lost an election, he tried to prevent the peaceful transfer of power as a violent mob breached the Capitol. But they failed," Biden said.

"And on this day of remembrance, we must make sure that such an attack never, never happens again," he added.

In a statement shortly after the US president's address, Trump claimed that Biden "used my name today to try to further divide America," although Biden did not mention Trump by name during his speech.

"The Democrats want to own this day of January 6 so they can stoke fears and divide America. I say, let them have it because America sees through (their) lies and polarizations," Trump said.

One year after the deadly attack on the Capitol, Democrats and Republicans still differ sharply over its key aspects, aftermath and the related congressional investigation, underscoring an increasingly partisan Congress, a more divided country and growing distrust in American democracy.

Democrats have denounced the Capitol riot as an attack on democracy, while most Republicans have downplayed its implications, especially Trump's alleged role in inciting it.

The US has not learned the lessons of the riot which led to multiple deaths, over 100 injuries and damage to the Capitol, US experts warned. As US partisan politics continues to decay, they say the country still faces the risk of a repeated incident.

More than half of Americans say that US democracy is at risk of extinction, including 49 per cent of Democrats and Republicans, as well as 54 per cent of Independents, according to a recent survey conducted by Schoen Cooperman Research.