A jury was sworn in on Monday for the trial of Hunter Biden on gun charges, the first-ever prosecution of a child of a sitting US president.

Hunter Biden, 54, the only surviving son of President Joe Biden, went on trial at the federal courthouse in Wilmington, Delaware, just days after Donald Trump, the president's likely opponent in November, was convicted on business fraud charges.

The proceedings, with another trial in which Hunter faces tax evasion charges in California, complicate the Democrats' efforts to keep the focus on Trump, the first former president found guilty of a crime.

Hunter is accused of failing to disclose his use of illegal drugs when he bought a Colt Cobra .38 caliber revolver, and of illegally possessing the weapon for 11 days in October 2018.

If convicted, he could face up to 25 years in prison and $750,000 in fines, though first-time and nonviolent offenders are often given shorter terms.

Opening statements were scheduled to begin on Tuesday, and the first witness to provide testimony is an FBI agent who was responsible for investigating the case.

The trial comes after the collapse of a plea deal with federal investigators last year. Hunter pleaded not guilty in September after being indicted by special counsel David Weiss, a Trump appointee, and has denied the charges.

The collapsed plea deal led to Hunter's indictment on three felony gun charges in Delaware and nine tax charges in California, in a trial set for Sept 5 in which he is accused of avoiding to pay at least $1.4 million.

First lady Jill Biden was in court on Monday for jury selection for Hunter's trial. The president did not attend, but said he and Jill were "proud" of their son.

In October 2018, Hunter purchased a revolver at a gun store north of Wilmington, the Bidens' hometown. Prosecutors will seek to prove that Hunter knew he was lying when he ticked the box "no" next to a question on a federal gun purchase form asking if he was an unlawful user of a controlled substance.

Hunter has been open about his longtime struggles with crack cocaine addiction, including in his 2021 memoir Beautiful Things, and discussed it during a court hearing last year, stating he has been sober since 2019.

Agencies contributed to this story.