Facebook and Twitter have taken aim at US President Donald Trump and his campaign over a video post in which he contended that children are "almost immune" to the coronavirus, a claim they said amounted to "misinformation".

In an extraordinary move, Facebook removed the clip from the president's account - the first time it has taken down one of his posts for violating its content rules.

A Facebook spokesperson said the video - an excerpt from a Fox News interview - "includes false claims that a group of people is immune from Covid-19 which is a violation of our policies around harmful Covid misinformation".

Twitter meanwhile said it had blocked Mr Trump's official campaign account over a tweet containing the same video, in which Mr Trump made the case for reopening US schools next month.

A Twitter spokesperson said the tweet was "in violation of the Twitter rules on Covid-19 misinformation", adding that the campaign would have to remove it before being allowed to tweet again.

Shortly afterwards, the @TeamTrump account was active, suggesting the contested video had been taken down.

"Another day, another display of Silicon Valley's flagrant bias against this president, where the rules are only enforced in one direction," the Trump campaign's deputy national press secretary Courtney Parella said in a statement.

"The president was stating a fact that children are less susceptible to the coronavirus," she said. "Social media companies are not the arbiters of truth."

Health officials have urged people of all age groups to protect themselves against exposure to the coronavirus.

Mr Trump has been calling for both businesses and schools to reopen as part of a push to revive the US economy, whose health will play a major factor in the coming presidential election.

A growing number of US school districts have opted however against in-person classes come September, opting to remain online-only until the pandemic has abated.

Mr Trump has been repeatedly accused of spreading misinformation about the coronavirus pandemic - which has killed more than 150,000 Americans - including the now-infamous musing that virus victims could perhaps be injected with disinfectant.

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