The second presidential debate between US President Donald Trump and Democrat Joe Biden has been cancelled.

The nonpartisan Commission on Presidential Debates confirmed on Friday that the October 15 event would be scrapped.

Mr Trump had expressed reservations about holding the debate "virtually" after he contracted Covid-19, as was suggested by the commission on Thursday.

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Meanwhile, Joe Biden scheduled a town hall with ABC News for that night once Mr Trump said he would not participate.

Mr Trump's team later countered with a call to hold the debates as scheduled once the president's doctor said he would be cleared to hold public events beginning on Saturday.

But the commission said it would not reverse its decision not to have the candidates on stage together, citing an abundance of caution with health concerns - particularly for the town-hall-style debate that was set to feature questions from average voters.

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The third debate, scheduled for October 22 in Nashville, Tennessee, is still on.