The US system of electing presidents is archaic and distorts the will of the people, Russian Foreign Minister Sergei Lavrov has said.

Joe Biden won the popular vote by more than five million ballots in the United States last week but that translated to an extremely tight margin in the electoral college that ultimately decides the president.

Compared to other significant countries in the world, the US electoral system is "probably the most archaic", Mr Lavrov said.

During an online press conference he said the system "significantly distorts the will of the population".

Incumbent Donald Trump has refused to concede, instead mounting a series of legal challenges over the results.

Russian President Vladimir Putin - unlike many world leaders - has not congratulated Mr Biden on the win because of the court disputes.

Mr Putin by comparison sent a congratulatory note to President Trump in 2016 within an hour of his claim of victory.

Mr Lavrov explained that Russia could not congratulate Mr Biden until official results were announced.

"The State Department has also not yet recognised the presidential election," he said, noting that US Secretary of State Mike Pompeo has called for patience until all of the ballots are counted.

Mr Putin has already won four presidential elections and recently changed the constitution to allow him to remain president until 2036.

Mr Biden will be the fourth US president since Mr Putin came to power in 2000.

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