Federal investigators are reportedly looking into donations to President Trump Donald John TrumpOmar fires back at Trump over rally remarks: 'This is my country' Pelosi: Trump hurrying to fill SCOTUS seat so he can repeal ObamaCare Trump mocks Biden appearance, mask use ahead of first debate MORE's inauguration from donors with links to foreign entities.

Sources told ABC News that special counsel Robert Mueller Robert (Bob) MuellerCNN's Toobin warns McCabe is in 'perilous condition' with emboldened Trump CNN anchor rips Trump over Stone while evoking Clinton-Lynch tarmac meeting The Hill's 12:30 Report: New Hampshire fallout MORE's team has questioned several inauguration donors with personal or business connections to Russia, Saudi Arabia, the United Arab Emirates and Qatar.

Mueller's team has also interviewed longtime Trump friend Tom Barrack, who oversaw the inauguration fundraising efforts, and also operates a fund with hundreds of millions in real estate and other holdings in the Middle East.

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Barrack brought in more than $107 million for Trump’s inauguration.

Multiple donors who gave up to $1 million to the Trump inauguration fund have links to the named countries, according to public records reviewed by ABC.

Mueller’s team has reportedly been asking witnesses about Leonard Blavatnik and Andrew Intrater, two American businessmen who made major donations to the inauguration and have business ties to Russia, according to ABC News.

Mueller is investigating whether the Trump campaign colluded with Russia, and has so far indicted 13 Russian nationals and three Russian groups on charges related to meddling in the election.

He has also charged a number of former Trump campaign officials on criminal financial charges unrelated to their work on the campaign.

Updated at 12:13 p.m.