Moroccan authorities have arrested six people in a long-running investigation into doping in the country's track and field federation.

Federation spokesman Mohammed Nouri tells The Associated Press that the investigation was initially launched in 2007, renewed in 2013, then renewed again this year.

He says six people have been arrested over the course of the investigation, but would not give their identities or other details while the probe is ongoing. The Interior Ministry has not commented.

Moroccan website Medias24 reported Tuesday that the federation's director alerted authorities last month to suspicions of doping by Moroccan athletes competing in national and international competitions.

The track world has been rocked by doping scandals that are casting a shadow over the upcoming Olympics in Rio de Janeiro.