US President-elect Joe Biden

Biden certified Georgia winner after hand recount

It comes as legal efforts by Donald Trump's allies to challenge his defeat were dismissed in three other states.

The Democrat beat his Republican rival in Georgia by 12,670 votes, according to the audit required by state law.

Mr Raffensperger on Friday said he was disappointed that his party lost but that "numbers don't lie".

Mr Biden is set to take office in January as the 46th US president.

US President-elect Joe Biden urges mask-wearing to save 'thousands of lives'

Biden said the US faced a "very dark winter" and the "worst wave yet", and Americans had to put aside political differences to tackle Covid-19.

He has named a new task force and vowed to "follow the science" as he puts together his transition team.

Donald Trump still refuses to concede defeat and is challenging key results. He is taking legal action in several states.

Biden's victory was declared on Saturday but it remains a projection, with a number of states still counting ballot papers. He leads Trump in the nationwide vote by about 4.5 million.

Joe Biden vows to unify country in victory speech

"Let's give each other a chance," he said at an event in Delaware addressing those who did not vote for him.

Mr Biden defeated incumbent President Donald Trump following a cliff-hanger vote count after Tuesday's election.

Mr Trump has yet to concede and has not spoken publicly since his defeat was announced while he was playing golf.