Special counsel Robert Mueller’s team of investigators grilled several witnesses about millions of dollars in donations to President Trump’s inauguration committee, a new report said Friday.

The donors they asked about had links to Russia, Saudi Arabia, the United Arab Emirates and Qatar, sources told ABC News.

Those interviewed included longtime Trump pal Tom Barrack, who was in charge of the fundraising for the president’s inauguration.

The billionaire runs a fund with hundreds of millions in real estate and private equity holdings in the Middle East, the network reported, and hauled in a record $107 million, twice what was spent on President Barack Obama’s first inauguration.

Several donors with ties to the four countries contributed more than $1 million for the gala.

And while those donations are a matter of public record, ABC’s report was the first to reveal that Mueller was asking questions about them, and it remained unclear what sparked his interest.

Investigators have also asked about specific donors, including American businessmen Leonard Blavatnik and Andrew Intrater, according to sources familiar with the Mueller sessions.

Neither has been accused of any wrongdoing, but Intrater heads up Columbus Nova, a company with ties to Viktor Vekselberg, a Kremlin-connected Russian oligarch.

Columbus Nova gave Trump fixer Michael Cohen’s shell company, the same one used to pay $130,000 in hush money to porn star Stormy Daniels, $500,000, and he gave $250,000 to the inaugural committee.

Blavatnik, a billionaire with dual US and British citizenship, has extensive business ties in Russia and gave $1 million to the inaugural fund through his company, Access Industries, FEC records show.

The donations in and of themselves are legal, but Mueller’s team is likely trying to determine if there was any possible quid-pro-quo with any members of the Trump campaign.

Intrater and Vekselberg attended Trump’s inauguration, according to multiple media reports.

Vekselberg, a Ukraine-born Russian national, was also questioned by Trump’s team on a visit to the US.

The president has repeatedly denied any collusion with Russia, and has slammed the probe as a “witch hunt” and “fake news.” He has also denied having a one-night stand with Daniels in 2006, as she and her lawyer have charged.