Olympic champion Brianna Rollins-McNeal has been provisionally suspended for a doping rules violation, the Athletics Integrity Unit (AIU) said on Thursday.

Rollins-McNeal won gold in the 100-meter hurdles at the 2016 Rio de Janeiro Olympics. The 29-year-old American was also world champion in 2013.

The AIU said it charged Rollins-McNeal with "tampering within the results management process," but did not specify details of the case.

The AIU cited a section in the World Anti-Doping Code that covers "conduct which subverts the doping control process."

The code gives one example as "altering identification numbers on a doping control form during testing."

Rollins-McNeal is the fourth-fastest woman in history in her event. She clocked 12.26 seconds at the U.S. national championships.