MOSCOW - The new Russian parliament chosen in a fraud-tainted election will go ahead with its first session, President Dmitry A. Medvedev said Tuesday, showing no inclination to bend to unprecedented nationwide protests that drew tens of thousands into the streets.

Medvedev acknowledged the vote-fraud complaints but said lawmakers would meet next Wednesday anyway, ignoring demands that officials annul the election and start over.

"The State Duma must begin work," he said at a meeting with leaders of the four parties that won parliamentary seats in the Dec. 4 vote. "We must continue working on our legislation because that is the whole reason behind having a parliament."

Leaders of two of the parties were openly critical of the elections after the meeting with the president. One maintained that the vote was "illegitimate."

The Saturday protests in some 60 Russian cities, including a throng of tens of thousands in Moscow, have left Medvedev, Prime Minister Vladimir V. Putin, and members of the United Russia party searching for a strategy that will defuse widespread anger without weakening their position.

Even with the reported vote fraud, United Russia reached only a narrow majority, losing about 20 percent of its seats in parliament and revealing voter frustration at ingrained corruption and the wide gap between everyday Russians and the country's plutocrats.

Medvedev told leaders of the four parliamentary parties that "we must continue work not only on economic issues, but on reforming the political system, ... take more decisive steps to remove barriers on political activity."

Much of Russia's opposition political forces have been heavily marginalized by the authorities. Election law sets registration requirements so high that smaller parties cannot muster enough signatures to compete. It requires at least 5 percent of the national vote even to get a token single seat.

The three other parties that won seats in parliament either do not offer significant opposition to United Russia or generally vote in step with it. But they were outspoken.

"We consider these elections illegitimate from both the moral and the political point of view," Communist Party leader Gennady Zyuganov told reporters.

Medvedev said in the meeting that he believed election commissions and courts should take a look at violation complaints.