MOSCOW (Reuters) - The last Soviet leader Mikhail Gorbachev said on Saturday Russia will face unrest unless society is made more democratic despite President Vladimir Putin's success in cracking down on dissent.

Gorbachev, whose perestroika (restructuring) and glasnost (openness) reforms in the 1980s failed to avert the collapse of the Soviet Union, has sympathized with protests, mainly by the rising urban middle class, against alleged ballot fraud and political corruption.

"The authorities have managed to beat down the wave of protest for a while, but the problems have not disappeared. If everything remains as before, they will escalate," Gorbachev was quoted by the RIA news agency as saying in a lecture.

"This means that we face a new attempt by Russian society to move to real democracy and it will be of historic significance."

The warning by Gorbachev, active in public life at the age of 82 and co-publisher of the independent Novaya Gazeta newspaper, came as Putin, who won a third presidential term a year ago, seeks to consolidate power.

Rather than engaging in dialogue with opponents, Putin has sought to marginalize them, while ratcheting up foreign policy rhetoric to create an atmosphere of a nation under siege.

In the past week, officials searched offices of foreign non-governmental organizations, Putin ordered snap military exercises in the Black Sea and he created a 'hero of labor' honor reminiscent of a Soviet command economy.

Russia's economic growth has more than halved since before the 2008 financial crisis and is now close to stagnating, reflecting its reliance on oil export revenues.

Experts call for long-term structural reforms to reducing the state's role in the economy, addressing pressures caused by an ageing population, and cutting red tape and corruption.

Gorbachev said Russia risked stagnation.

"We have come to the point when we have cut off perestroika. Politics is increasingly turning into imitation. We need a new system of the governance of the country," said Gorbachev.

(Reporting by Maya Dyakina; Editing by Jason Webb)