Young black people are nine times more likely to be jailed than young white people, according to new analysis from the Ministry of Justice.
The findings were released on Friday ahead of next week's expected publication of the final report of the review into race and the criminal justice system, headed by Labour MP David Lammy.
The number of young people aged between 10 and 17 years old held in custody has reduced "substantially" across all ethnic groups since 2007/08, the MoJ found.
But volumes for black, Asian and minority ethnic (BAME) groups have been falling at a slower rate than the white group. As a result, the BAME share of the custodial population has increased in the past ten years.
The MoJ analysis revealed that about nine in every 10,000 young black people in England and Wales were in youth custody in 2015/16 - the highest proportion in any ethnic group.
In comparison, one in every 10,000 young people from white ethnic backgrounds, four in every 10,000 of those from mixed race backgrounds and two in every 10,000 of those classified as "Asian and other" were in youth custody.
The government research showed that young black people were more likely to be identified with "gang concerns" and be considered a "risk to others" on entry to custody than any other ethnic group between April 2014 and March 2016.
In the last four years, young black people have spent longer in custody than young white people, the analysis found, with the sentence lengths for violence against the person, theft and possession of weapons driving this trend.
The arrests of young black people were probably a contributing factor to the high number of young black people sentenced to custody, the report found, but there was also evidence of disproportionality in custodial sentences at the magistrates' court.
"The analysis in this report indicates that the high proportion of young black people in custody is likely to be driven by arrest rates (i.e. the gateway to the criminal justice system), custodial sentencing at the magistrates' court, and the fact that they have spent longer in the custodial estate on average than other groups in the past four years," the report reads.
The study also said that proven reoffending rates for young white people who left custody between 2010 and 2014 were higher than for young black people.
"Therefore high proven reoffending rates for those returning to custody are unlikely to be a contributing factor in the disproportionately high number of young black males in custody," the review says.