President Barack Obama became the first sitting US president to visit a federal prison on 16 July to push his plans for a fairer justice system and prison reform.

The president travelled to El Rino prison in Oklahoma, where he met with law enforcement officials and non-violent drug offenders, Voice of America reported.

"We've got to be able to distinguish between dangerous individuals who need to be incapacitated and incarcerated versus young people who ... if given different opportunities, a different vision of life, could be thriving," the president said after his meeting with six inmates at the El Reno Federal Correctional Institution outside of Oklahoma City, the Los Angeles Times reported.

Obama called for a reduction or elimination of mandatory minimum sentences for non-violent drug crimes earlier this week. Some reforms would include a reconsideration of solitary confinement and a rise in job training programmes for incarcerated people.

In his speech, the president called on Congress to pass a sentence reform bill by the end of the year, according to the Voice of America. He blamed the strict sentences for drug offences for the doubling of prison population in the US over the last two decades.

However, the LA Times noted that if the president orders the Department of Justice to change how it files charges, many more criminal cases will be handed down to state and local prosecutors.

"A lot of this ... is going to have to happen at the state level," Obama said. "My goal is that we start seeing some improvements at the federal level and we're then able to see states across the country pick up the baton."

The president said that while many of those in prison belong there, including "murderers, predators, rapists, [and] gang leaders," many young black and Latino men have been treated unfairly by law enforcement compared to their white counterparts.

Obama has seized on national calls for change in the justice system that sprouted with the death of Michael Brown in Ferguson, Missouri and have continued with the deaths of Eric Garner in New York, and Freddie Gray in Baltimore, Maryland.

According to the LA Times, the president commuted the sentences of 46 inmates prior to his visit to the federal prison on 16 July.