About 43,000 Russian citizens have reportedly been punished for not declaring a second passport or foreign residency permit since a deadline for reporting dual citizenship expired two months ago.
Those found to be in violation of the law were fined between 500 rubles ($9) and 1,000 rubles ($18), though no criminal cases have so far been brought, the Kommersant business daily reported on Friday, citing an unnamed parliamentary source.
State agencies that oversee the hunt for those holding dual citizenship, including the Federal Migration Service, have yet to comment on the report.
Under a law passed in June, Russians with a second passport or foreign residency permit were obliged to report themselves to authorities by Oct. 4.
Failure to do so could lead to an administrative or criminal case being brought, with the latter carrying penalties of up to 400 hours of community service or a fine of 200,000 rubles ($3,700).
The rules may be softened by the year's end, the State Duma source was cited as saying.
Under a new bill, Russians who missed the deadline because they were living abroad will be exempt from liability, but will be required to inform the authorities about their extra passports or foreign residency permits within 30 days of setting foot on Russian soil.
About 600,000 Russians disclosed second citizenship or foreign residency permit by the deadline, according to official figures.
But according to estimates by the think tank Migration XXI Century in Moscow, the total number of Russians holding multiple passports and/or residing abroad is estimated by experts at up to 10 million, the RBC Daily news site reported earlier.
Russia does not explicitly prohibit holding a second passport, but limits the rights of dual citizens, who have been banned from serving as state officials since 2004.
Migration experts said at the time of the law's passing that it would help them in their hunt for members of Russia's "fifth column," fueled by the Kremlin's souring relations with the West.