Dubai police say Sulim Yamadayev, who led a battalion in Chechnya, was shot dead in a car park near his luxury apartment, and have accused a senior Chechen politician of organizing the killing. However, Yamadayev's brother Isa insists that Sulim survived the assassination attempt, and is still alive.
Speaking to reporters on a flight from Turkmenistan to Moscow, Foreign Minister Sergei Lavrov said Russia is waiting to receive "any kind of official report" on the murder from the United Arab Emirates.
"We are counting on our partners in the Emirates do this quickly... The official channel for such cases is the embassy. However, nothing had been received as of the day I left Moscow [Thursday]."
Lavrov had been in the Turkmen capital, Ashgabat, for a ministerial meeting of the post-Soviet Commonwealth of Independent States members.
Almost two weeks on from the killing, doubt remains as to Yamadayev's fate. Isa and family members say he is in intensive care, and the Russian embassy in Dubai says it has not received documented confirmation of Yamadayev's death.
Dubai police said earlier this week they have conclusive evidence that Yamadayev was assassinated by Adam Delimkhanov, a Chechen member of Russia's parliament closely associated with Chechen President Ramzan Kadyrov.
Kadyrov has furiously denied Delimkhanov's involvement in the assassination, saying on Monday that: "Adam Delimkhanov is my close associate, a friend, a brother and my right hand man." He pledged to "hold responsible those who make slanderous insinuations."
The shooting follows a string of assassinations of prominent critics of the Chechen leadership. In September last year Yamadayev's brother Ruslan was shot dead in his car in central Moscow, and in January a former bodyguard of Kadyrov, Umar Israilov, was killed on a street in Vienna.
Sulim Yamadayev served as the commander of Russia's Vostok battalion in Chechnya, but fled the republic last year after a clash between his troops and Kadyrov's guards.
The incident has focused international attention on Chechnya, and prompted analysts to suggest that the Russian government is failing to keep Kadyrov under control, as the republic becomes increasingly authoritarian.
Chechnya was devastated by two military campaigns, in 1994-1996 and 1999-2001, after which Moscow significantly scaled down its military presence in the republic.