"I think we must do everything to ensure that democracy doesn't backslide, that it is preserved," Gorbachev said at the presentation of a report by his foundation marking the 20th anniversary of his pioneering program of perestroika, or restructuring, which caused the first cracks in the Soviet empire.
Gorbachev said perestroika ended totalitarianism and gave birth to freedom in the then-Soviet Union, and today there is "no turning back."
But he criticized Putin's annulment of direct elections for governors and district elections for parliament and said he disagreed with the way the state had conducted the campaign against the Yukos oil company, particularly the arrest of its former CEO, Mikhail Khodorkovsky — though he voiced support for the policy of going after tax cheats.
Gorbachev also objected to the growing state control over Russian media.
"The one thing I can say is that it's pointless today to watch television," he said.
At his summit with Putin last week, President Bush expressed concerns about democracy in Russia. Putin said Russia is committed to democracy but will take its traditions history and level of development into account.
Gorbachev, whose nearly seven years in power ushered in a period of free speech that helped to shed light on the worst excesses of the dictator Josef Stalin, warned that the legacy of Stalinism was a threat that still needed to be combated.
"Stalinism is a special Russian form of slavery. We have to fight the remnants of Stalinism, I say this every day," he said.
Gorbachev was widely reviled after the 1991 Soviet collapse, and when he ran for president in 1996 against the man who replaced him in the Kremlin, Boris Yeltsin, Gorbachev picked up barely 1 percent of the vote.
"It is slowly improving," he said of the popular attitude to the Gorbachev era, which many Russians blame for the loss of Moscow's superpower status.
Putin, who was overwhelmingly re-elected to a second term a year ago, is credited with restoring stability in Russia after the chaos of the post-Soviet era, although his popularity has suffered this year amid a wave of protests over cuts to social benefits.
Gorbachev has largely refrained from criticizing the current Russian leader, although he joined in an unsuccessful campaign to try and save the independent NTV television network from falling into effective state hands in 2000.
By Henry Meyer