ARLINGTON (REUTERS) - United States President Joe Biden used his Memorial Day speech on Monday (May 31) to defend the country's "imperfect" democracy, calling for more work to deliver the promise of what he said remained "the greatest experiment" in world history.

In a speech at Arlington National Cemetery touching on voting rights, freedom of speech and efforts to rectify persistent economic and racial disparities, Mr Biden warned that democracy was "in peril" in the US and around the world in the face of autocratic forces he did not identify.

"Democracy is more than a form of government, it's a way of being, a way of seeing the world. Democracy means the rule of the people," Mr Biden said in a speech to honour one million Americans who have lost their lives in military service.

"The struggle for democracy is taking place around the world - democracy and autocracy. The struggle for decency, dignity, just simple decency," he said.

Speaking in the largely empty Arlington Memorial Amphitheatre with the nation still in the grip of the coronavirus pandemic, Mr Biden said 7,036 people had died in recent US conflicts in Iraq and Afghanistan, serving the ideals of the US and democracy as a vibrant form of government. "They lived for it, they died for it," he said.

"We owe the honoured dead... our full best efforts to perfect the Union for which they died." Mr Biden has announced plans to withdraw US troops from Afghanistan this year after the longest ever US overseas engagement. He has also pointed to what he has describes as autocratic rule in China and Russia as major challenges faced by the US.

As many US states work to pass laws that critics argue are intended to suppress minority voting, Mr Biden also stressed the need for people to have the right to vote "freely and fairly and conveniently" and for the rule of law to apply "equally and fairly to every citizen, regardless of where they come from, what they look like".