Ex-leader Gorbachev Slams Russia's Putin

* Gorbachev accuses Putin of not offering political choices

* Says Medvedev's modernisation drive failing

By Denis Dyomkin

MOSCOW, Feb 21 (Reuters) - Former Soviet leader Mikhail Gorbachev criticised Prime Minister Vladimir Putin on Monday for monopolising power in Russia and robbing the electorate of what he says was a real democratic choice.

Putin, who ruled as president from 2000-2008, is widely seen as Russia's paramount leader. He has said President Dmitry Medvedev, whom he steered into the Kremlin three years ago, and he will decide together who will stand in the March 2012 presidential elections.

In some of Gorbachev's harshest criticism yet of the current set up, he slammed Putin as "shameless" and accused him of "conceit" in thinking he could decide Russia's elections. "It is shameless ... such conceit is unbelievable," Gorbachev, whose bold reforms helped trigger the 1991 collapse of the Soviet Union, told reporters.

"This is not Putin's business. It is the business of the nation. It is the business of elections. It is the business of those who will vote," he said.

"Are others not even allowed to run?"

Gorbachev joins a marginalised Russian opposition who accuse Putin of wielding too much power, disregarding many freedoms and not holding fair elections.

In the two decades since the Soviet collapse, Russia "has come no more than half-way" on the path toward democracy, Gorbachev said.

"We have a parliament, courts, a president, a prime minister ... But you know that this is little more than imitation," he said.

Likening Putin's ruling United Russia party to the Soviet Communist Party, Gorbachev said democratic institutions in today's Russia were broken because the pro-Kremlin party dominated in parliament.

"United Russia looks to me like the worst copy of the Soviet Communist Party," he said, adding that such political monopolies lead to "stagnation".

Gorbachev told Reuters last year that the Kremlin's economic modernisation drive that Medvedev is championing would not succeed without improvements in democracy and the electoral system.

Last week Gorbachev said the popular revolts in Egypt and Tunisia were a warning to autocrats the world over. (Writing by Alissa de Carbonnel)