Russia's top investigative agency says the powerful mayor of the regional capital of the restive southern province of Dagestan has been detained on charges of organizing an investigator's killing.

The Investigative Committee's spokesman, Vladimir Markin, said that Said Amirov, the mayor of Makhachkala, was detained Saturday along with more than ten accomplices. He said that Amirov is accused of staging the killing of the Investigative Committee's officer in 2011.

Amirov is a legendary figure who has wielded vast clout in the Caspian Sea region, which has been destabilized by an Islamist insurgency that has spread across Russia's North Caucasus after two separatist wars in Chechnya.

He has been in a wheelchair since an assassination attempt in 1993, and has a private army of several hundred security guards.