Tajik opposition leader Umarali Kuvvatov has been shot dead by an unknown assailant on an Istanbul street, Turkey's private Dogan news agency said on Friday.
Kuvvatov, who had been living in exile in Turkey and was head of the "Group 24" opposition movement, was killed with a single shot to the head at around 10:30 pm (2030 GMT) on Thursday evening in the Fatih district of the city, it said.
The attacker then fled the scene, Dogan added.
Istanbul police declined to comment on the case.
Turkey's anti-terrorism police unit and murder squad are handling the investigation into the killing of the 47-year-old, who had been eating dinner at a house in the area before the killing, Dogan said.
Kuvvatov, an outspoken critic of Tajikistan's veteran strongman leader Imomali Rakhmon, was already dead when medics arrived at the scene and police searched the area for evidence, it said.
Kuvvatov's "Group 24" movement was declared an "extremist organisation" and banned by Tajikistan's Supreme Court last October. Tajik law enforcers wanted him for a number of crimes, including extremism, economic crimes and hostage-taking. Turkey had declined to extradite him.
Kuvvatov had also lived in Russia and the United Arab Emirates in recent years before settling in Turkey.