Hundreds of demonstrators demanding a rerun of Russia's December 4 parliamentary elections gathered Saturday in central Moscow to protest alleged election fraud in December 4 polls won by Prime Minister Vladimir Putin's ruling United Russia party.

The turnout was much smaller than the nationwide protests last Saturday, which drew tens of thousands of people to the Bolotnaya Square across the river from the Kremlin in the largest protest demonstration in post-Soviet Russia.

The rally was organized by the liberal Yabloko party that failed to make it into the parliament. Grigory Yavlinsky, the party's founder, told the crowd the goal is to change the political system in Russia.

Another protest, which is expected to attract a larger crowd, is planned for December 24.

Also Saturday, the United Russia party nominated Sergei Naryshkin to become speaker of the State Duma, the lower house of parliament. Naryshkin worked in the 1980s in the economic attache's department of the Soviet embassy in Belgium.

On Friday, U.S. President Barack Obama raised questions about the disputed parliamentary elections in a phone call with his Russian counterpart, Dmitry Medvedev.

A White House statement said that President Obama noted reports of flaws in the way the elections were conducted, but welcomed Mr. Medvedev's commitment to investigate the allegations.

Mr. Obama also praised the response of Russian authorities to allow demonstrations against the elections to take place. He said the protests are an expression of civil society that is consistent with Mr. Medvedev's goal of modernizing Russia.

Separately, the White House said that during the telephone call, Mr. Obama also congratulated Russia on receiving an invitation to join the World Trade Organization. The statement said both presidents hailed this achievement as yet another result of the reset in bilateral relations, and will benefit both the U.S. and Russia.