US President Joe Biden's son Hunter was indicted Thursday for illegally buying a gun when he was using drugs, casting a new shadow over his father's campaign for reelection next year.

Hunter Biden, 53, was charged with two counts of making false statements when claiming on forms required for the 2018 gun purchase that he was not using drugs illegally at the time.

A third charge said that, based on the false statements, he illegally possessed the gun during an 11-day period in October that year.

If convicted on all three felony charges, Biden could in theory face 25 years in prison, though in practice they are seldom punished by any jail time.

In attesting that he was not an unlawful user of drugs when he bought the Colt Cobra revolver, Biden "knew that statement was false," the Justice Department said.

The indictment came two days after Republicans in Congress opened an impeachment probe against Democrat Joe Biden, alleging that when he was vice president he benefitted financially from his son's foreign business dealings.

The legal troubles of Hunter Biden present a target for political rivals of his father, who is bidding for a second term in the White House.

Hunter is a Yale-trained lawyer and lobbyist-turned-artist, but his life has been marred by alcoholism and crack cocaine addiction.

Without offering any evidence, Republicans have accused Biden's Justice Department of protecting his son and have accused Weiss, a Republican appointee, of going easy on Hunter.

Representative James Comer, a Republican from Kentucky who will be leading the impeachment inquiry, welcomed the filing of the gun charges, calling it a "very small start."

"Mountains of evidence reveals that Hunter Biden likely committed several felonies and Americans expect the Justice Department to apply the law equally," Comer said.

Twice-impeached former president Donald Trump reacted on his Truth Social platform.

"This, the gun charge, is the only crime that Hunter Biden committed that does not implicate Crooked Joe Biden," he said.

– Plea deal collapsed –

But a leading Democrat, Keisha Lance Bottoms, ex-mayor of Atlanta and a former senior adviser to Joe Biden, questioned why Hunter had been charged.

"Can anyone tell me how many people have been federally indicted for purchasing a gun while dealing with substance abuse issues?" Bottoms said on X, formerly known as Twitter.

"I don't know the answer, but in my over 29 years as an attorney, I have never heard of it."

The gun charges were filed by Justice Department special counsel David Weiss, who has been investigating Hunter Biden since 2018 over various allegations, mostly related to his overseas business deals.

Two months ago a plea deal between Biden and Weiss, covering the gun charge as well as alleged tax violations, went sour.

Biden agreed to plead guilty in federal court in Delaware to two minor tax charges. In exchange he was offered probation, as he had already paid what he owed the government along with penalties.

Weiss agreed to suspend the felony gun charge if Biden completed "pretrial diversion," which often involves counseling or rehabilitation.

But in a dramatic July 26 hearing, the deal collapsed over whether Biden would have been immune from any other charges also investigated by Weiss, including possible crimes related to his business dealings in Ukraine, China and elsewhere.

The judge mentioned the possibility that Biden could be charged as having acted as a lobbyist for foreign governments without registering with the Justice Department.

Three weeks later, after the deal collapsed, Weiss dropped the tax charges and said an indictment on the gun charge would come by the end of September.

As the 2024 election race swings into gear, Republicans in the House of Representatives on Tuesday formally opened an impeachment inquiry against President Biden.

They alleged, without offering hard evidence, that while vice president in 2015-2016, Biden intervened to protect an allegedly corrupt Ukrainian energy company, Burisma, where Hunter Biden sat on the board.

Republicans allege Joe Biden and his family reaped large sums for helping Burisma.