More than 30 of those arrested in Dar Ul-Arham were foreign nationals, CNN reported Friday.
Members of Russia's Federal Security Service and police conducted the raid.
Suspected radicals, some of them from the North Caucasus region, have reportedly visited the site in the past.
Biologists detail four new deep-sea 'killer sponges'
Pistorius testifies he didn't consciously pull trigger when he shot girlfriend