The social network said it would label or remove misinformation aiming to undermine confidence in the election, such as posts which claim victory prior to the announcement of the result or those citing unlawful conduct.

Its attempts to crack down on such posts follow the 2016 election which saw Russia meddle in the election in order to sway it towards a victory for Donald Trump.

The policy goes into effect on September 17, a few weeks before the election on 3 November.

Many Americans are expected to vote by mail due to the Covid-19 pandemic, which is likely to delay election results.

Trump has repeatedly claimed, without citing evidence, that voting by mail is susceptible to large-scale fraud.

Twitter also said it would label or remove misinformation creating confusion about the laws, regulations and officials involved in civic processes, as well as disputed claims that could undermine faith in the process, such as unverified information about vote tallying or election rigging.

A Twitter spokesman said whether content had specific falsehoods or could cause greater harm would determine if it would be removed, or labelled and have its reach reduced.

Facebook also said last week it will restrict new political ads in the week before the election and remove posts that convey misinformation about Covid-19 and voting.

It will also attach links to official results to posts by candidates and campaigns that prematurely declare victory.

“We will not permit our service to be abused around civic processes, most importantly elections,” Twitter said in a blog post on Thursday.

“Any attempt to do so — both foreign and domestic — will be met with strict enforcement of our rules, which are applied equally and judiciously for everyone.”

Though the policy comes weeks before the US election, more than 80 per cent of Twitter’s users are outside of the US and it will apply globally.

Last month Twitter introduced new conversation settings for brands allowing them to put out messages and public statements about sensitive issues without prompting debate on the platform.