NEW YORK • Hip-hop superstar Jay-Z last Friday called for concerted action to reform probation in the United States, saying the prison term handed to rapper Meek Mill showed an unjust system that ensnares black men.

Jay-Z, who had taken to social media and stopped a concert to press Mill's case, wrote in an op-ed for The New York Times: "What's happening to Meek Mill is just one example of how our criminal justice system entraps and harasses hundreds of thousands of black people every day.

"Instead of a second chance, probation ends up being a land mine, with a random misstep bringing consequences greater than the crime."

A Philadelphia judge on Nov 6 sentenced Mill, 30, to two to four years in prison for probation violations, raising audible gasps in the courtroom.

Judge Genece E. Brinkley's ruling came after a prosecutor and a probation officer recommended against prison time.

Mill, who is signed to Jay-Z's entertainment company Roc Nation, has been appearing before the judge since a 2008 arrest for gun and drug possession.

His probation violations include a recent arrest for a fight at a St Louis airport, a case in which charges were dropped. Judge Brinkley's decision has set off protests, including a rally by hundreds of supporters outside the Philadelphia courthouse.

Mill said he was badly beaten by the police when they arrested him in 2008 and used a bloodied mugshot of himself as the cover of his 2016 mixtape, DC4.

His recent album, Wins And Losses, made its debut at No. 3 on the Billboard album chart in August.

Probation, which dates from English common law, was initially seen as a way for courts to grant freedom to people who posed little risk to the community.

But a recent survey by The Marshall Project, a non-profit news organisation, found that at least 61,250 people and probably far more are in prison across the US for minor parole violations such as missing appointments, failing drug tests or staying out past curfew.

"The system treats them as a danger to society, consistently monitors and follows them for any minor infraction - with the goal of putting them back in prison," Jay-Z wrote.

Of the 4.65 million people on probation, parole or supervised release across the US in 2015, 30 per cent were African-American, according to Justice Department figures.

AGENCE FRANCE-PRESSE, NYTIMES