A radical wing of the Chechen rebel leadership confirmed that the notorious Arab warlord Khattab was dead, in a statement to the separatist news agency Kavkaz-Center.
"The death of the Chechen commander has been officially confirmed," the news agency said, citing the "command headquarters of the Chechen Mujahideen," adding that Khattab was poisoned by a letter delivered to him on March 19.
Russia's intelligence agency FSB, the former KGB, said last week it had killed the shadowy guerrilla leader, believed to have been born in Jordan or Saudi Arabia and known by only by the single name Khattab, during an undercover operation.
However, Chechen rebels repeatedly dismissed the claims as Moscow's propaganda, even after Russian RTR state television broadcast several minutes of amateur film apparently showing the body of Khattab, recognisable by his trademark flowing black hair and beard.
The film was shot by Chechen rebels on March 19-20 and later obtained by the FSB, according to RTR.
The Chechen radical wing said Khattab was poisoned by a letter delivered by a messenger who was known to him, adding that "according to some information, the messenger is now with the Russians," Kavkaz-Center reported.
The report added that Khattab was buried in the mountain regions of southern Chechnya, a stronghold of separatist rebels who have been fighting a brutal two and a half year guerrilla war against Russian forces.
Khattab, who according to Russia had links to wanted terrorist suspect Osama bin Laden's al-Qaeda network, personified for many Russians the threat of international Islamic extremism.
The death of such a prominent figure would represent a major blow to the rebels in breakaway Chechnya where Russian forces have until now failed to kill or capture any of the leading Chechen guerrilla chiefs.
Khattab, head of the Islamic Army of Dagestan, was the loyal lieutenant of top Chechen commander Shamil Basayev, with whom he had sought to restore a 19th-century Islamic state in the Caucasus.
He is a figure shrouded in mystery, an enigma that begins with his name and origins. Russian newspapers say he was in his mid-30s, and born Habib Abder-Rakhman of Jordanian or Saudi origin.
Viewed as one of the main proponents of Wahhabism, an austere Saudi brand of Islam, he is said to have waged a holy war against Russia for 15 years, first in Afghanistan then in Tajikistan and to have also supported Muslims in Azerbaijan during the conflict in Nagorny-Karabakh.
Russia says he arrived in Chechnya during the first Chechen war from 1994-96 and in August 1999 led armed incursions into the Russian republic of Dagestan.
Some 1,500 fighters were said to be under his command in the southern mountains of Chechnya.