WASHINGTON—Half the federal agents who were investigated for allegedly attending sex parties with prostitutes in Colombia received financial bonuses during the investigation or afterward, according to a new internal review of the Drug Enforcement Administration’s handling of the scandal.

Justice Department inspector general Michael Horowitz issued a report on Thursday analyzing the aftermath of the internal probes of DEA agents in Colombia for allegedly patronizing prostitutes. The allegations were originally investigated in 2010, but the issue created a firestorm earlier this year when the details became public.

DEA administrator Michele Leonhart was criticized by lawmakers who said she didn’t sufficiently discipline the agents. She defended her actions by saying she had limited control over the agency’s disciplinary process, but later resigned.

DEA policy prohibits employees from receiving promotions, awards or other favorable personnel actions for a three-year period after being subject to discipline for significant misconduct or while a misconduct probe is continuing, though officials are allowed to create exceptions to the policy.

None of the 14 DEA agents who fell under scrutiny for alleged sexual misconduct or harassment was promoted during that three-year period. But the inspector general’s office found 10 instances where DEA officials approved bonuses for employees “even though they had been subject to discipline for significant misconduct within three years or while a misconduct investigation was still in progress,’’ according to the report.