The social media giant said the accounts broke its rules on spam and platform manipulation.

Many of the accounts used identical language, including the phrase: "YES IM BLACK AND IM VOTING FOR TRUMP!!!"

Twitter has not specified the number of accounts suspended so far or the source of them.

It said it was continuing to investigate the activity and may suspend additional accounts if they were found to be violating its policies.

The investigation was first reported by the Washington Post newspaper.

Darren Linvill, a social media disinformation researcher at Clemson University, found more than two dozen such accounts, which had generated some 265,000 retweets or Twitter mentions.

Some of the accounts used photos of black men that had appeared in news articles. Several had tens of thousands of followers.

Mr Linvill told Reuters news agency that most of the accounts were created in 2017, but had become more active in the past two months.

He said all of the accounts he had been monitoring had now been suspended but that they had "already had their impact".

Twitter forbids using the platform "to artificially amplify or suppress information or engage in behaviour that manipulates or disrupts people's experience" on the site.

Its action comes weeks ahead of the 3 November US presidential election.

Polls suggest about 10% of black voters are supporting Mr Trump, according to polling website FiveThirtyEight.