WASHINGTON, Jan 6 (AFP) - President Joe Biden on Thursday (Jan 6) savaged Donald Trump's "lies" and attempt to overturn the 2020 election, vowing on the first anniversary of the Jan 6, 2021 Capitol riot that he would let no one put a "dagger at the throat of democracy".

After largely ignoring Trump for a year, Biden took off the gloves, describing the Republican as a cheat whose ego would not let him accept defeat and whose supporters almost shattered US democracy when they stormed Congress to prevent certification of the election.

"This was an armed insurrection," Biden said in his dramatic speech from Statuary Hall inside the Capitol, where a year ago thousands of people brandishing Trump flags trampled over police to invade the chamber, forcing lawmakers to flee for their lives.

"For the first time in our history, a president not just lost an election. He tried to prevent the peaceful transfer of power," Biden said.

"They came here in rage," Biden said of Trump's backers, and "held a dagger at the throat of America".

"I will allow no one to place a dagger at the throat of democracy."

Biden's voice filled with anger as he laid out the dangers facing a country that has long styled itself as leader of the free world.

"Are we going to be a nation that accepts political violence as a norm?" he asked.

Although Biden deliberately did not mention Trump's name, he made clear whom he was talking about in a blistering portrait of a man he said scorned democracy because he couldn't accept defeat.

"The former president of the United States of America has created and spread a web of lies about the 2020 election," Biden said. "He values power over principle."

During the assault on Congress, Trump was "sitting in the private dining room off the Oval Office in the White House, watching it all on television and doing nothing for hours", Biden said, his anger clear. "He's a defeated former president."

Trump, who has spent the last year spreading conspiracy theories about his election loss to millions of followers, quickly fired back with a series of statements doubling down on his lie about the "rigged" election and dismissing Biden's speech as "political theatre".

"Never forget the crime of the 2020 Presidential Election. Never give up!" read Trump's latest statement.