MOSCOW (AP) -- Doku Umarov, a Chechen warlord who had threatened to attack the Sochi Olympics and claimed responsibility for some of Russia's deadliest terror attacks in recent years, was reported dead on Tuesday by the Islamic militant group he led. One of Russia's most wanted men, he was 49.
Umarov's death has been claimed repeatedly in the past, but this appeared to be the first time such a report has come from the organization he headed.
The Caucasus Emirate announced the ''martyrdom'' of Umarov in a statement posted Tuesday on Kavkaz Center, the website of Islamic militant groups in Russia's North Caucasus. The region includes the provinces of Chechnya and Dagestan. No cause of death was given.
As the leader of the Caucasus Emirate, a loose alliance of rebel groups seeking to create an independent Islamic state in the region, Umarov was seen more as a spiritual leader than a commander directing terror attacks. The impact of his death on the Islamic insurgency was not yet clear.
Umarov fought against Russian troops in the Chechen war of 1994-96, when separatists won a measure of independence, and he took up arms again when the second war broke out in 1999. By then the Chechen struggle for independence was being transformed into a wider Islamic insurgency.
In recent years, Chechnya has become more stable under the Kremlin-backed leader, Ramzan Kadyrov, whose security force has been notorious for its brutality, but the insurgency has swept into other Caucasus provinces.
In 2007, Umarov created the Caucasus Emirate in 2007 and proclaimed himself emir.
He has claimed responsibility for major terror attacks in Russia, including the suicide bombing in Moscow's Domodedovo airport in January 2011 that killed 37 people and injured more than 180, and twin suicide bombings on the Moscow subway in March 2010 that killed 40 people and injured more than 120.
In 2012, Umarov ordered a halt to attacks on civilian targets because of the mass anti-Kremlin demonstrations in Moscow. He reversed that order last July, urging his men to ''do their utmost to derail'' the Sochi Olympics, which he described as ''satanic dances on the bones of our ancestors.''
Concerns about the threat were heightened by back-to-back suicide bombings in late December in the southern city of Volgograd, which killed 34 and wounded 100 others. Militants based in Dagestan, citing Umarov's call, claimed responsibility for those attacks.
For the Sochi Winter Games in February, Russia introduced sweeping security measures to protect athletes and fans.
In January, Kadyrov announced Umarov's death, citing information he said came from intercepted communications between rebel leaders discussing his replacement.
Kadyrov said Tuesday that he had now been proven right.
''This has been confirmed by the rats themselves,'' Kadyrov said on his Instagram account. ''What else do the special services and the mass media need to believe in the death of the terrorist?''
Russia's National Anti-Terrorist Committee said it had no information about whether Umarov had died and would not comment on the report, the state RIA Novosti news agency said.