Russian secret service operatives "neutralised" Chechen rebel leader Doku Umarov in the first quarter of 2014, Russia's top intelligence chief confirmed.
Head of Federal Security Service of Russia (FSB) Aleksandr Bortnikov said that Umarov, the leader of the Caucasian Emirate terrorist organisation, was killed in a "combat operation".
Umarov, the leader of the Islamist insurgency in the North Caucasus, was not only Russia's most wanted man but also on the wanted lists of the United States and the United Nations Security Council for his terrorist activity within Russia.
The rebel leader fought for the creation of a "Caucasus Emirate" - of which he was to be the self-proclaimed emir - and has taken responsibility for numerous attacks.
Some of the attacks Umarov organised include a suicide bombing that killed 37 people at a Moscow airport in January 2011 and the "Nevsky Express" 2009 train explosion which killed 28 people.
Bortnikov said that Russia stepped up its counter-terrorism efforts during the Sochi Winter Olympic and Paralympic Games.
"During the Winter Olympics, we kept stepping up efforts to curb criminal activity of gangs rampaging in several North Caucasian republics," he said.
"In the first quarter of 2014, 36 anti-terrorism operations have been carried out in line with our operational plan. Among significant results is the neutralisation of 13 warlords and 65 active gang members. More than 240 bandits and their accomplices were detained," the FSB director said.
Chechnya is a separatist region within Russia, tarnished by years of war between rebels and Russian forces.
Moscow ended its military operations in the region in 2009 but the province still acts as a hotbed for terrorist activity with incidents such as the 2011 triple suicide bomb, detonated in the Chechen capital Grozny, killing six people.