More than 3,000 crack cocaine inmates in Washington had their sentences cut after the federal government decided to ease penalties for drug crimes that are usually committed by blacks, informed a federal Sentencing Commission study released on Thursday.

In December, the U.S. Sentencing Commission voted to ease penalties for drug crimes, in an attempt to reduce the disparity in crack-related crimes, mostly committed by blacks, versus crimes involving powdered cocaine, which are usually linked to white people. The study found that four out of five crack convictions involve black people.

Since the new federal sentencing guidelines, which took effect in March, around 3,600 crack cocaine inmates have applied for early release, and federal judges agreed to cut the sentences for around 3,000 of them.

About 1,600 federal inmates were eligible for immediate release, but the study does not reveal the number of those who have been released so far.

Worried about the large number of releases, the Justice Department suggested that only the first-time, non-violent offenders should benefit of reduced sentences. But the proposal was unsuccessful, so now prosecutors are concerned that thousand of violent criminals might be released following the new guidelines.

The report issued Thursday shows that 30 percent of the crack offenders receiving cut sentences were small-time of first-time criminals, while 9 percent of them were violent or repeat offenders.