US President Joe Biden has issued an official pardon for his son Hunter, who was facing sentencing for two criminal cases, despite previously ruling it out.

In a statement, the president said his son had been "singled out" and called his cases "a miscarriage of justice".

Hunter Biden pleaded guilty to tax charges earlier in September and was found guilty of being an illegal drug user in possession of a gun in June - becoming the first child of a sitting president to be convicted of a crime.

Reacting to the pardon, President-elect Donald Trump said: "Does the Pardon given by Joe to Hunter include the [6 January] Hostages, who have now been imprisoned for years? Such an abuse and miscarriage of Justice!"

Trump was referring to his supporters who stormed the US Capitol on 6 January 2021 in a bid to overturn Trump's defeat in the 2020 election.

Joe Biden's full and unconditional pardon for his son comes after the president had previously said he would not give him clemency.

Just a couple of months ago, in September, the White House press secretary said that Biden would not issue a pardon for his son.

But on Sunday evening, President Biden said although he believed in the justice system, "politics has infected this process and it led to a miscarriage of justice".

"From the day I took office, I said I would not interfere with the Justice Department’s decision-making, and I kept my word even as I have watched my son being selectively, and unfairly, prosecuted," he said.

Biden said he wrestled with the decision and added: "Once I made this decision this weekend, there was no sense in delaying it further."

"I hope Americans will understand why a father and a President would come to this decision," he said.

In a reaction statement, Hunter Biden said mistakes he made during the darkest days of his addiction had been "exploited to publicly humiliate and shame" his family for political sport.

"I will never take the clemency I have been given today for granted and will devote the life I have rebuilt to helping those who are still sick and suffering," the 54-year-old added.

The younger Biden has been sober for five-and-a-half years, his father said.

This is not the first time a US president has pardoned a member of their family.

Bill Clinton pardoned his younger half-brother, Roger Clinton, for a 1985 cocaine-related offence in 2001.

In 2020, Donald Trump pardoned Charles Kushner, the father-in-law of his daughter Ivanka. President-elect Trump has recently announced Kushner as ambassador to France in his new cabinet.

Hunter Biden pleaded guilty to nine counts of federal tax fraud in September, for which he had been facing up to 17 years in prison.

He was also convicted of three felonies in connection with a gun purchase in June, for which he had been facing up to 25 years in prison.

Sentencing for these cases had been scheduled for 12 and 16 December.

His legal troubles had been a dark cloud over his father's presidential campaign, which came to an end in July after Biden pulled out of the election race.

Biden endorsed Vice-President Kamala Harris to succeed him as the Democratic candidate, who lost the election to Republican Donald Trump in November.

Trump is set to take over the Oval Office from Biden on 20 January 2025 - Inauguration Day.