MOSCOW, July 19 (RIA Novosti) - Russia's Supreme Court has significantly reduced prison terms for retired Russian military intelligence colonel Vladimir Kvachkov and his co-conspirator earlier sentenced for plotting an armed uprising.

Kvachkov, 64, was sentenced by Moscow City Court in February to 13 years in high-security prison while retired police officer Alexander Kiselyov, 62, was sentenced to 11 years in general population prison for his part in the alleged plot.

The Supreme Court on Thursday reduced Kvachkov’s sentence to eight years, dropping charges of “terrorist activities.” Kiselyov’s sentence was reduced to five and a half years.

Their defense lawyers immediately said they would appeal the court’s ruling in the European Court of Human Rights demanding all charges be dropped and their client exonerated.

Kvachkov was previously twice acquitted after being accused of an assassination attempt in 2005 on former Unified Energy Systems head Anatoly Chubais, one of the key architects of a notorious privatization drive in Russia in the early 1990's.

Kvachkov was acquitted by the Supreme Court of the attack on Chubais on December 22, 2010, but the next day the Lefortovo District Court sanctioned his arrest as part of the investigation into the alleged coup attempt.

According to case materials, Kvachkov, as head of the headquarters of the Minin and Pozharsky public militia group, “plotted to seize weapons in several military units and organize an armed march on Moscow for the forceful overthrow of power.”

Kvachkov has denied all charges against him but defended during the trial “the right of Russian citizens to hold an uprising."

A career military officer, Kvachkov commanded a Special Forces unit in Afghanistan in 1983. In 1984, after sustaining a head injury, he was awarded the highly prestigious Order of the Red Star and later received the Order of Courage.