MOSCOW, September 2 (RIA Novosti) – Russian police have arrested 229 suspected illegal immigrants during a raid on a market in Moscow, the Interior Ministry said Monday.

The raid, in the capital’s southwest, took place on Friday, though the ministry announced it only Monday afternoon.

Police were checking a produce market on the city’s Novoyasenevsky Prospekt when they found an “additional second floor” with rooms for foreigners to live in at a building near the subway station, the ministry said in a press release.

“229 people were taken to the [police] stations for checks,” the ministry said.

Police have conducted a series of sweeps and mass checks of markets and other locations with large concentrations of immigrant workers over the past month, after a policeman was injured by a mob while trying to detain a man suspected of rape at a Moscow market at the end of July.