US federal prosecutors have filed criminal charges against George Santos, the embattled Republican US congressman who has previously admitted to "embellishing" his resume but defied calls to step down, CNN reported on Tuesday, citing three sources.

Mr Santos is expected to appear as soon as Wednesday in federal court in New York's Eastern District, where charges have been filed under seal, CNN reported.

A spokesperson for the US Attorney's office for the Eastern District of New York declined to comment.

The Associated Press reported that in a brief phone interview Mr Santos said he was unaware of the charges.

"This is news to me," AP quoted Mr Santos as saying. "You're the first to call me about this."

Mr Santos' office did not immediately respond to a request for comment, and his lawyer could not immediately be reached.

Republican House Speaker Kevin McCarthy said he would withhold judgment on Mr Santos, saying, "in America, you're innocent until proven guilty".

CNN reported that the exact nature of the charges against Mr Santos were not immediately clear.

However, federal prosecutors have been examining false statement allegations in Mr Santos' campaign filings.

In March, the US House of Representatives Ethics Committee launched a probe looking at a variety of concerns, including whether Mr Santos engaged in illegal activity over his 2022 campaign, failed to properly disclose information required on House statements, and violated federal laws concerning his role in a financial firm.

Mr Santos' office, through his congressional Twitter account, has previously said he is cooperating with the House Ethics Committee's investigation.

Mr Santos was elected in November in a wealthy district of New York's Long Island in a race where concerns about crime weighed heavily on voters' minds. It was a bright spot for Republicans in what was otherwise a lackluster election night for the party.

The race drew outsized attention as both major candidates self-identified as gay, and Mr Santos was the first non-incumbent Republican who identifies as a member of the LGBTQ community to win a seat in the US House of Representatives.

But reporting by the New York Times and other media outlets in December called into question almost every element of Mr Santos' life story.

Among other claims, Mr Santos said he had degrees from New York University and Baruch College, despite neither institution having any record of him attending. He claimed to have worked at Goldman Sachs and Citigroup, which also was untrue.

He said falsely that he was Jewish and that his grandparents escaped the Nazis during World War Two, and he failed to disclose that he was married to a woman for several years ending in 2019.

Following those revelations, Mr Santos apologised for "embellishing" his resume, while defending aspects of the way he had represented himself.

For instance, he has since described himself as "Jew-ish" rather than "Jewish" when discussing his heritage, telling the New York Post he described himself that way because his "maternal family had a Jewish background".

Broaden your horizons with award-winning British journalism. Try The Telegraph free for 1 month, then enjoy 1 year for just $9 with our US-exclusive offer.