D.C. police officer Leroy T. Smith has been officially reprimanded for spanking a 13-year-old youth who was caught stealing potato chips and cookies from a Northeast supermarket, police department officials said yesterday.

Smith spanked the boy last Feb. 17 after the store manager turned him over to Smith and another officer. Smith said afterward that he decided the 13-year-old needed discipline, and, with the permission of the boy's guardian, "I put him across my knee and whomped him four times."

However, police department regulations forbid officers from striking children, even if parents or guardians give permission.

Smith, a 12-year veteran of the force, was taken off his regular beat and assigned to stationhouse duty for five months while the incident was investigated by the U.S. attorney's office, which declined to prosecute him.

The police department's disciplinary review office, which could have fined or fired Smith for the offense, determined earlier this week after its own lengthy investigation that a reprimand, the lightest possible department penalty, was sufficient punishment.

"We got a barrage of calls in support of the officer" after the incident was reported in the media last month, said Assistant Chief Theodore Carr, who oversees the disciplinary office. "The officer has a good record and appeared to be acting in good faith. But we could not justify the behavior . . . We decided [the reprimand] was the least penalty considering the circumstances."