US Democratic presidential nominee Joe Biden’s campaign accused Facebook Inc in a letter to Mark Zuckerberg of being "the nation’s foremost propagator of disinformation about the voting process.”

The letter, sent on Sept 28 by campaign manager Jen O’Malley Dillon, said Facebook’s actions to remove disinformation about mail-in voting have fallen behind despite the company’s public commitment to aggressively fight inaccurate information.

"As you say, ‘Voting is voice’,” O’Malley Dillon wrote. "Facebook has committed to not allow that voice to be drowned out by a storm of disinformation, but has failed at every opportunity to follow through on that commitment.”

The Biden campaign’s letter is the latest in an ongoing effort to get Facebook to be more aggressive about removing misinformation from its platform, specifically coming from the president and his allies. The campaign sent a handful of letters over the summer, accusing the company of applying more lenient standards to President Donald Trump.

O’Malley Dillon criticised the company on Sept 29 for failing to remove a video from Donald Trump Jr in which he said his father’s opponents have a "plan to add millions of fraudulent ballots that can cancel your vote and overturn the election.” O’Malley Dillon said the campaign flagged the video to Facebook but that it was not removed.

"No company that considers itself a force for good in democracy, and that purports to take voter suppression seriously, would allow this dangerous claptrap to be spread to millions of people,” she wrote. "Removing this video should have been the easiest of easy calls under your policies, yet it remains up today.”

Facebook said it responded to the flagged content by applying fact-checking labels to it, and the company said it has removed content from the president in the past when "it’s run afoul of our policies.

"While many Republicans think we should take one course, many Democrats think we should do the exact opposite,” a spokesman for Facebook said in a statement. "We’ve faced criticism from Republicans for being biased against conservatives and Democrats for not taking more steps to restrict the exact same content. We have rules in place to protect the integrity of the election and free expression, and we will continue to apply them impartially.”

Since the 2016 election, when Russian trolls used fake accounts to try to sway the outcome, Zuckerberg has promised a more robust commitment to removing disinformation, particularly around politics, on its platforms.

 - Bloomberg