ROSTOV-ON-DON, April 24 (RAPSI) - Former Makhachkala Mayor Said Amirov and  his  nephew Yusup Dzhaparov on Thursday pleaded not guilty to terrorism charges, RIA Novosti reported from the North-Caucasian District Military Court in Rostov-on-Don.

A long-term member of the ruling United Russia party, Amirov has served as mayor of Makhachkala since 1998.

On October 28, Amirov was charged with terrorism and illegal arms trafficking. Investigators found that the defendants planned to fire at a plane carrying Amirov's political opponent Sagid Murtazaliyev by a man-portable air defense system.

Earlier, Amirov was also charged with the 2011 murder of investigator Arsen Gadzhibekov in the Dagestani city of Kaspiysk. On June 1, 2013, he was arrested and transported to Moscow, where he was taken into custody. Amirov has denounced the case as politically motivated.

Gadzhibekov was fatally shot near his home as he was getting out of his car. He had worked on a number of criminal cases, including the 2010 terror attack in Kizlyar that killed 10 and injured 270.

The investigators believe that Amirov ordered the assassination, which was organized by Magomed Abdulgalimov, assistant city prosecutor of Kizlyar with accomplices, Deputy Mayor of Kaspiysk Yusup Dzhaparov and Kirovsky District police investigator Magomed Akhmedov. The murder was committed by Magomed Kadiyev, the Investigative Committee claimed earlier.

On June 4, charges were officially brought against Amirov.

Amirov was detained after his arrest. Earlier in March his detention was extended until June 1.