The lawyers for Vakhit Murdashev, Viskhan Khajimuradov, Iles Iriskhanov and Iskandarbek Yusupov insist that a Chechen court's decision to sentence the men to prison terms between five-and-a-half and 15 years should be overturned, calling it "illegitimate and unfounded."
The appeal hearing is set for March 22.
Russian law-enforcement authorities accused Maskhadov, the rebellious region's president in 1996-2000, for masterminding a number of high-profile terrorist attacks, including a hostage-taking raid on a Moscow theater in 2002 and a school siege in the southern town of Beslan in 2004.
One of Russia's most wanted men, with a $10 million bounty on his head, Maskhadov was trapped by federal forces outside the Chechen capital last March and killed after he refused to surrender.
