US House panel investigating January 6 insurrection and Donald Trump's attempt to overturn 2020 election opens prime-time hearing, declaring lies that led to riots put "two and half centuries of constitutional democracy at risk."

US Capitol riot probe chief says rioters acted at the
US Capitol riot probe chief says rioters acted at the "encouragement" of then-president Donald Trump and the assault was a "culmination of an attempted coup." (AFP)

A congressional panel investigating last year's deadly Capitol riot has opened its first public hearing, at which it intends to make the case that Donald Trump and his claims of a stolen election were at the heart of a conspiracy that drove the mob assault.

In a live, prime-time presentation of its findings from a year-long probe on Thursday, the special committee is seeking to persuade a divided country of the existence of a deep-rooted and ongoing plot to undermine core tenets of the US Constitution and overturn the result of the 2020 election.

The conspiracy that drove the insurrection by a pro-Trump mob still poses a threat to American democracy, Democratic committee chief Bennie Thompson warned in his opening remarks at the panel's first hearing.

Thompson said the committee's work was about more than looking backward, as US democracy "remains in danger."

"The conspiracy to thwart the will of the people is not over," he said.

"There are those in this country who thirst for power but have no love or respect for what makes America great: devotion to the Constitution, allegiance to the rule of law, our shared journey to build a more perfect Union."

READ MORE: 'Trump broke the law', says January 6 panel

Trump 'at the centre of that effort'

The panel aims to demonstrate that the violence was part of a broader drive by Trump and his inner circle to illegitimately cling to power, tearing up the Constitution and more than two centuries of peaceful transitions from one administration to the next.

"We will be revealing new details showing that the violence of January 6 was the result of a coordinated multi-step effort to overturn the results of the 2020 election and stop the transfer of power from Donald Trump to Joe Biden," a select committee aide said.

"And indeed that former president Donald Trump was at the center of that effort."

Rioters acted "at the encouragement of the president of the United States," Thompson said in his opening remarks.

READ MORE: Top US court rejects Trump bid to keep Capitol attack records secret

Trump defends insurrection

A slickly produced 90-plus minutes of TV on Thursday – and five subsequent hearings over the coming weeks – will focus on Trump's role in the multi-pronged effort to return him to the Oval Office by disenfranchising millions of voters.

Trump has defiantly dismissed the probe as a baseless "witch hunt" – but the public hearings were clearly on his mind on Thursday as he launched into a largely false tirade on his social media platform, defending the insurrection as "the greatest movement in the history of our Country to Make America Great Again."

The case the committee plans to make is that Trump laid the groundwork for the insurrection through months of lies about fraud in an election described by his own administration as the most secure ever.

His White House is accused of involvement in several potentially illegal schemes to aid the effort, including a plot to seize voting machines and another to appoint fake "alternative electors" from swing states who would ignore the will of their voters and hand victory to Trump.

READ MORE: Biden administration vows to hold Capitol attackers accountable

Source: TRTWorld and agencies