Former Soviet leader Mikhail Gorbachev is in hospital "determined to fight for his life", Russian state media sources are reporting.
He is cited as telling Interfax news agency that his health was deteriorating, but that he was "determined to fight for his life".
Former Soviet Union leader Mikhail Gorbachev has said the crisis in Ukraine stems from the government's failure to act democratically, according to the Associated Press.
He spoke a day after demonstrators took over the capital Kiev and seized the president's office as parliament voted to remove him and hold new elections.
Mr Gorbachev said that the root cause of the unrest in Ukraine was an "interruption of perestroika", referring to his reform policies, and of the democratic process.
The former Soviet president Mikhail Gorbachev has been admitted to the Kremlin hospital for routine tests, his spokesman told the Associated Press.
The 82-year-old complained of health problems in March, and declined to attend Margaret Thatcher's funeral for health reasons in April.