MOSCOW, Oct. 31 — The system for deploying international observers to monitor elections in the states of the former Soviet Union appeared near collapse today after Russia formally declared its intention to cut sharply the size of the mission that will monitor parliamentary elections in December, and European officials refused to agree immediately to the change.

Russia had already made the work of this year’s mission difficult by delaying the invitation to the monitoring group, and the group says this has prevented it from carrying out preliminary work.

Today, the group, the monitoring arm of the Organization for Security and Cooperation in Europe, said it had received the invitation, but it included unprecedented restrictions. Russia said it would allow only a maximum of 70 observers to take part in a short-term mission. The group sent 400 observers for the parliamentary election four years ago.

Urdur Gunnarsdottir, a representative of the monitoring arm, the Office for Democratic Institutions and Human Rights, or O.D.I.H.R., said in a statement today, “We need to consider the implications of those restrictions, as they may seriously limit the possibility for a meaningful observation according to our standard methodology for full-scale election observation missions.”

Speaking to reporters, Igor Borisov, an official of Russia’s Central Election Commission, dismissed the importance of the European mission. “Russia does not need to invite an army of observers because the Russian electoral system is one of the most advanced in the world,” he said.

The move to reduce the presence of European observers for the parliamentary ballot on Dec. 2 reflects the Kremlin’s growing control over the election process under President Vladimir V. Putin.

Already, the Kremlin has pushed through changes in the election laws that have made it all but impossible for most opposition politicians to win seats in the next Parliament. Mr. Putin’s party, United Russia, which dominates the government, is expected to win an even greater majority in the Parliament in December.

Last month, Russia circulated a proposal at the Organization for Security and Cooperation in Europe to limit permanently the work of the election observers in the former Soviet Union by cutting the size of missions and preventing them from issuing public statements about a government’s electoral conduct in the days after citizens voted.

The O.D.I.H.R. has regularly dispatched observation teams to elections throughout the states of the former Soviet Union since the collapse of Communism.

Russia and other post-Soviet countries have repeatedly criticized the reports of the monitors, which often show that voting is marred by fraud and that opposition groups are not allowed to operate freely.