"Democracy has prevailed,'' newly inaugurated US President Joe Biden said on Wednesday in his maiden speech as he called on Americans ''to defend the truth and defeat the lies''.

''This is America's day..democracy has prevailed,'' Biden said, apparently referring to his Trump's efforts to deny him victory in the November 3 election won by him.

''With unity we can do great things," he said referring to the challenges ahead of him from fighting the coronavirus to addressing racial injustice.

''Unity is the path forward,'' he asserted, laying out his vision to defeat the pandemic, build back better, and unify and heal the nation.

Biden asserted that he will be the president for all Americans, all those who voted for him and those who did not vote for him.

In his speech that lasted for 21 minutes, Biden praised Americans for rising to the challenge and reclaiming democracy. He mentioned the attempt to undo it at that exact location two weeks ago, and renewed his campaign goals of overcoming the pandemic, bringing racial justice and fighting climate change.

Biden also criticised those who have stoked anger and division, and asked those who opposed him to "hear me out." He called out those who lie for political power and profit. "There is truth, and there are lies," he added.

In a message to the international community, Biden said that he would rebuild the alliances frayed over the past four years. ''We can make America once again the leading force of good in the world.'' ''We will repair our alliances and engage with the world once again, not to meet yesterday's challenges but today's and tomorrow's challenges," he said.

"We will lead by the power of our example," he said in his message to the international community.