Kasyanov did not specify which country and for how long he left, Kommersant reports.
“Yes, I went abroad. I hope not for long”, - TASS quoted Kasyanov as saying.
The departure of Kasyanov from the country became known the day before, on June 2, according to Konstantin Merzlikin, a member of the bureau of the political council of PARNAS.
Kasyanov served as prime minister from 2000–2004 during Vladimir Putin's first presidential term. After retiring, he joined the ranks of the opposition.
His associates were the politician Boris Nemtsov, who was killed near the walls of the Kremlin, Vladimir Ryzhkov, Ilya Yashin, Vladimir Kara-Murza, Sergey Aleksashenko, Vladimir Milov and others.
After the start of the military special operation of the Russian Federation on the territory of Ukraine, Kasyanov condemned its conduct and took part in the work of the "Anti-War Committee".