MOSCOW, August 16 (RIA Novosti) – An immigrants’ rights campaigner is facing up to five years in jail for trying to get 4,500 foreigners registered in his organization’s office in Moscow, police said Friday.

The charges against Pavel Kovalenko follow a string of raids on immigrant workers across Russia this month. Kremlin critics say the crackdown is part of an attempt by official candidates to bolster their support base by appearing tough on illegal immigration ahead of local elections on September 8.

Kovalenko, secretary of the Defense migrant rights group, filed a request with the migration authorities to register more than 4,500 people in the group’s office, spokeswoman for Moscow’s South-Western police district Yulia Anosova told RIA Novosti. She said Kovalenko faces up to five years in jail for organizing illegal immigration.

Under Russian law, all foreigners must be registered at a hotel or private residence within seven days of arrival, or face fines or deportation. Thousands of Russians profit on the procedure by registering dozens or even hundreds of foreigners, mostly immigrant workers from ex-Soviet nations, in their apartments or houses, that have been dubbed “rubber homes.”

Kovalenko reportedly claimed his group helps immigrants get registered free of charge and find a job. He told the Yopolis.ru website that his group had registered about 60,000 migrants at its offices in Moscow.

“We do it because that’s what the law proscribes,” he was quoted as saying. “We stand for labor migration.”

He said he and his group “fell victim to a PR campaign ahead of the mayoral election.”

Late last year, Russian President Minister Vladimir Putin proposed tougher measures to deal with illegal immigration including the expulsion of migration law-breakers and barring them from re-entering Russia for up to ten years. He also proposed legal proceedings against the owners of “rubber homes” where migrants register illegally, and criminal proceedings for those who take on illegal migrants at work and organize illegal housing.

Earlier this month, a Moscow resident received a suspended two-year sentence for registering four labor migrants from Uzbekistan in his apartment for 6,000 rubles ($185), while earlier this year, a criminal case was opened against a St. Petersburg resident for registering 2,750 foreign nationals at his home.

Economic growth driven by revenues from oil exports and a dwindling domestic labor force have made Russia a magnet for millions of labor migrants, mostly from the former Soviet republics of Central Asia. Some 11.3 million foreigners entered Russia this year, of whom 3 million work illegally, Federal Migration Service chief Konstantin Romodanovsky said in late July.