Brown University says it's reducing sanctions against a fraternity accused of allowing two female students to be drugged at an unauthorized party last year but won't overturn them.

The university said Saturday it reviewed its investigation of Phi Kappa Psi and will reduce a four-year suspension to 2½ years.

The fraternity appealed after a lab test that showed a student testing positive for a date-rape drug was later deemed inconclusive.

The university said the test was only part of the evidence, and its review concluded the two students had been served alcohol or some drug putting them at risk.

The fraternity has said it supports Brown's efforts to protect students but doesn't believe its members served a spiked drink to either young woman. No individuals have been charged with sexual misconduct.