Russian President Vladimir Putin said in a condolence telegram sent on Wednesday that former Soviet leader Mikhail Gorbachev had had a "huge impact on the course of world history".
Gorbachev, the last leader of the Soviet Union, died on Tuesday aged 91.
Putin said Gorbachev "deeply understood that reforms were necessary" and strove to offer his own solutions to the problems faced by the Soviet Union in the 1980s.
(Reporting by Reuters; Editing by Gareth Jones)