The Federal Bureau of Investigation (FBI) has warned of two fake videos circulating online that aim to cast doubt on the US presidential election – the latest in a series of warnings from senior officials.

BBC Verify has found evidence linking the videos to a much larger operation based in Russia that has produced hundreds of fakes targeting the election in recent months.

In a post on X on Saturday, the FBI said the two videos spread rumors about voter fraud and Doug Emhoff, the husband of Democratic vice presidential candidate Kamala Harris.

The fake videos, which claim to be from the FBI and include the bureau’s logo, have not received a large amount of views from real people on X.

“These videos are not authentic, they are not from the FBI, and the content they depict is false,” The FBI statement said.

“Attempts to mislead the public with false content about FBI operations undermine our democratic process and seek to erode confidence in the electoral system.”

The content of the clips described by the FBI exactly matches the videos that are part of a batch of more than 300 that BBC Verify has found since the start of the year as part of an investigation with online research firm Logically.

The videos use compelling graphics and text to look like content from US government agencies, as well as over 50 news organizations – including the BBC, France 24 and Fox News.

The videos have been posted online almost daily for months and have recently focused on the US election, including clips promoting false claims about Harris and messages about unrest and “civil war”.

CheckFirst – an online analytics company based in Finland that independently investigated the network behind the videos – traced them to a Russian marketing agency and a Russian IP address.

“We can link the operation to Russia because of some assets that we know were produced by a Russian company,” said Guillaume Kuster, chief executive of CheckFirst.

“The other source of evidence is a data set that we had access to that shows that one of the machines that was used to send the emails (by the group) was in Russia.”

In addition, the videos produced by the operation were widely circulated on Russian-language Telegram channels.

CheckFirst found that the style, messages and themes of the videos align with other Kremlin-linked operations, an assessment supported by BBC Verify research.

However, it is unclear who is leading the operation and whether it is funded by the Russian government.

The Russian Embassy in Washington said in a statement that allegations of election interference by the country were “baseless.”

“All insinuations about ‘Russian machinations’ are malicious smears, concocted to be used in domestic political battles in the United States.”

According to X’s statistics, the clips have been viewed tens of thousands of times, but are posted by accounts with few followers and attract very few comments — signs that the views are being boosted by fake “bot” accounts.

The FBI declined to comment on the operation, but along with the agencies, the bureau has issued two other warnings in recent days about Russia-linked influence networks.

Last week, intelligence agencies said a video purporting to show a poll worker destroying mail-in ballots marked for Donald Trump in Pennsylvania was “fabricated and enhanced” by the Russians.