MOSCOW, March 22 (RIA Novosti) – There are an estimated 3 million illegal migrants in Russia, the Federal Migration Service (FMS) said on Friday.

“There are now over 3 million people who have stayed in the Russian Federation longer than they were legally permitted to,” FMS deputy head Anatoly Kuznetsov said.

All of those migrants entered the country legally, but failed to leave within the 90-day period stipulated by the law, he said.

The number of migrant workers in Russia is around 5 million, including 3 million illegals, according to the FMS. The number of foreign nationals coming to Russia continues to increase, said Kuznetsov.

“Compared with the same time last year, the number of migrants entering the country has grown 14 percent,” he said.

In late February, the head of Russia's Federation of Migrants asked President Vladimir Putin to grant an amnesty to the country's millions of illegal immigrants, Izvestia reported. Muhammad Amin Majumder said in his letter there are around 10 million immigrants illegally working in Russia who could be contributing tax revenue to the Russian economy if they were legalized.

Migration is a contentious issue for Russia, with widespread disquiet in some sectors of society about the increasing numbers of foreign workers coming to Russia to live.

According to the 2012 International Migration Outlook, issued last year by the Paris-based Organization for Economic Cooperation and Development (OECD), Russia is home to the world’s largest number of illegal migrants, accounting for almost seven percent of the country’s working population.