The two men detained as suspects in the criminal case dealing with opposition politician Boris Nemtsov's murder, are suspected of both organizing and perpetrating the crime, Russian Investigative Committee spokesman Vladimir Markin said.
In televised comments, Alexander Bortnikov, the director of the Federal Security Service, said that Anzor Gubashev and Zaur Dadayev were taken into custody on Saturday.
Russian President Vladimir Putin had been informed of the detentions, officials said.
"The individuals detained are, according to our investigation, involved in the organization and execution of the killing of Boris Nemtsov," the committee said in a statement.