Police yesterday blocked Kremlin opponents from holding unlicensed marches in Russia's two main cities over the economic crisis, witnesses said, and detained more than 150 activists.

Marches of Discontent have become a trademark protest by a coalition of small opposition groups from liberals to communists led by former world chess champion Garry Kasparov and writer Eduard Limonov, the head of outlawed National-Bolshevik party.

Witnesses said that police trucks sealed off two squares in central Moscow, where the Other Russia coalition wanted to start its march. Police cordons prevented a handful of opposition supporters from entering the squares.

Police detained two dozen elderly Soviet officers at Pushkinskaya Square and several opposition activists, including Limonov, at Triumfalnaya Square two kilometres away.

In St Petersburg, police blocked about 100 protesters who were planning to march down the city's main thoroughfare Nevsky Prospekt to Chernyshevsky Square, the venue of an officially allowed rally. Several opposition activists were detained.

Less than 500 protesters later turned up at the Chernyshevsky Square chanting: "No to police state!" and "Authorities, answer for the crisis!" The rally lasted for an hour and ended peacefully.

"They are saving their money," Sergei Gulyayev, a senior member of Other Russia coalition, told the rally. "They will not save the Russian economy."