Hunter Biden, the son of US President Joe Biden, has been found guilty of three gun charges that could see him jailed.

A federal court jury in the Bidens' home state of Delaware reached a verdict after three hours of deliberations over two days.

They found Hunter Biden guilty of lying on a form when he bought a Colt revolver in 2018, and illegally possessing the weapon for 11 days. Hunter Biden had declared he was not using illegal drugs when in fact he was a crack cocaine user.

It's the second guilty verdict in two weeks to rock the US election campaign, after Donald Trump was convicted of 34 counts of falsifying business records relating to a "hush money" payment to porn star Stormy Daniels.

The federal charges have a maximum prison sentence of 25 years, but legal experts say Hunter Biden is unlikely to receive close to the maximum as a first-time offender, and probation is a more likely outcome.

A sentencing date is yet to be set, but it's likely to be before the election on November 5.

Joe Biden has previously ruled out pardoning his son. In a written statement released after the verdict, he said he accepted the outcome and would respect the judicial process as his son considered an appeal.

Prosecutors had played lengthy excerpts of Hunter Biden's audiobook to help prove their case to the jury. In the book, Beautiful Things, Hunter Biden details his descent into alcoholism and drug addiction after his brother, Beau Biden, died from brain cancer in 2015.

Hunter Biden and his supporters looked devastated as they trailed out of the courtroom. Some appeared close to tears. As he left the building, Hunter Biden was flanked by the first lady, Jill Biden, and his wife, Melissa Cohen Biden, each holding his hand.

The first lady has been a consistent presence in court, sitting quietly in the front row in support of her stepson. Her only absence from the trial was to accompany Joe Biden at D-Day commemorations in France last week.

Her attendance was remarked upon in closing arguments, with prosecutor Leo Wise gesturing to the gallery as he told jurors that while they might have seen these people on the news, none of that mattered as no-one was above the law.

The verdict came in too quickly for Jill Biden to make it back to the courtroom, and she arrived as it was being handed down. 

Hunter Biden was the first child of a sitting president to be criminally tried. It followed an investigation launched by Trump-appointed Delaware US attorney David Weiss in 2018.

In June last year, Hunter Biden's lawyer's negotiated a plea deal with the Department of Justice, to avoid trial on the gun charges by pleading guilty to two relatively minor tax offences. 

But the deal collapsed after it was rejected by the court.

Hunter Biden is now also facing tax evasion charges in California, with a trial scheduled for September.