The US FBI said it was investigating after Donald Trump’s presidential campaign said its internal communications were hacked and the campaign blamed the Iranian government.
The former president had said that Microsoft informed his campaign that Iran had hacked one of its websites.
Mr Trump said Iran was “only able to get publicly available information”.
The FBI is also investigating an alleged hack targeting advisers to the campaign of US President Joe Biden and Vice President Kamala Harris, the Washington Post reported.
The FBI began the investigation in June, when Mr Biden was still running for president, suspecting that Iran was behind the attempts to steal data from two US presidential campaigns, the newspaper said, citing sources.
The Harris campaign did not immediately respond to a request for comment.
Ms Harris became the Democratic presidential nominee after Mr Biden withdrew his bid last month.
The Iranian government has denied that it hacked the Trump campaign.
The report added that the hackers took over an account belonging to a former political adviser and then used it to target the official. It did not provide further details on the targets’ identities.
Read more: Trump campaign says the team’s internal communications hacked by Iran