Moscow: A Russian court on Friday convicted four men for helping orchestrate twin suicide blasts in 2013 that killed 34 people, handing down sentences of up to 19 years in detention.
The attacks against the main railway station in the southern city of Volgograd and a trolleybus took place on two consecutive days in late December, sparking security fears only two months before Russia hosted the Winter Olympic Games.
Volgograd`s Dzerzhinsky District Court ruled four people guilty of conspiring to stage the blasts by giving shelter to the two suicide bombers and helping them leave the North Caucasus region, hidden in a truck carrying hay.
The bombers, Asker Samedov and Suleiman Magomedov, were helped in Dagestan by Alautdin Dadayev and Ibragim Magomedov, who "let them live in their houses and make the explosive devices" there, the Investigative Committee said in a statement.
Dadayev and Magomedov were sentenced to 19 years each in a strict penal colony, the statement said. They were arrested in February and police found "large quantities of weapons and ammunition" as well as home-made explosives in Magomedov`s house, the statement said.
Two others -- radical Islamist brothers Magomed Batirov and Tagir Batirov -- "bought 188 bales of hay and placed them in a Kamaz truck" to hide the bombers who travelled to Volgograd on the truck.
The brothers were sentenced to three years and ten months each.
Moscow has battled simmering insurgency for several years in the North Caucasus after fighting two wars with separatists in Chechnya. The violence subsequently spread through the predominantly Muslim region.
In Chechnya, Islamists claimed responsibility for a deadly raid in the capital Grozny on Thursday, where a shootout in the city centre and clashes involving armoured vehicles used by security forces left 20 people dead and several buildings barely standing.
Dagestan remains by far the most turbulent region with near weekly attacks by Islamists and 200 people dead from violence between militants and security forces in the first 11 months of 2014, according to the Caucasian Knot news website that tracks the Caucasus region.