NASHVILLE, Tenn. (AP) _ Blacks get prison sentences that average about three months longer than whites for similar federal crimes, according to a computer analysis of 80,000 convictions over a two-year period.

Richard Conaboy, chairman of the U.S. Sentencing Commission, and others told The Tennessean that drug sentencing in particular had been unfair to blacks.

A computer analysis by the newspaper found that blacks get prison sentences about 10 percent longer than whites.

Whites convicted in 1992-93 received an average sentence of 33 months, while blacks got 36 months, The Tennessean reported Sunday. The computer study examined all federal court convictions during the two years, comparing cases where the seriousness of the crime and criminal histories were equal.

Conaboy, whose commission sets federal sentencing policy and keeps the records The Tennessean analyzed, said the disparity could be explained by factors that are legitimate for judges to consider, including whether defendants have held steady jobs.

At the same time, however, he and others criticized drug sentencing practices.

Of the more than 3,000 people convicted of possessing or selling crack in 1993, 90 percent were black _ despite the findings of a national government survey that half those who said they used crack were white. Five grams of crack carries a mandatory five-year sentence, while an equal amount of powder cocaine is a misdemeanor, punishable by less than a year in jail.

``The drug of choice for whites doesn't carry as severe a sentence as the drug of choice for blacks,'' says Henry Martin, chief federal defender in Middle Tennessee.

That means low-level street dealers can face longer sentences than distributors who supply them with the cocaine used for crack.

Conaboy and Wayne Budd, the only black member of the sentencing commission, both recommended to the Senate Judiciary Committee last month that crack and powder cocaine offenders get more equal treatment.

If Congress takes no action before Nov. 1, the commission is free to set its own, new standards.

Crack cases alone don't explain the differences in sentencing. When drug convictions were excluded from The Tennessean's analysis, the disparity remained.

The study found the highest black-white sentencing disparity _ 13 percent _ in the West. The South had the lowest regional disparity, with 3 percent. Sentences for blacks were 12 percent higher in the Midwest and 10 percent in the Northeast.

Hispanics received sentences comparable to whites. Too few Asians and other minorities were convicted of federal crimes for a statistically valid comparison, the newspaper said.