A senior Russian official says about 10,000 immigrants who obtained Russian citizenship have been sent to the frontlines in Ukraine.
The Chairman of the Investigative Committee, Alexander Bastrykin, made the remarks on Thursday.
He said authorities have identified more than 30,000 foreigners who recently received Russian citizenship but were not registered with the military.
Bastrykin said the authorities have begun to implement the provisions of Russian laws that require persons who have received citizenship to register with the military and, if necessary, take part in the special military operation. He added that about 10,000 of them have been sent to the special military operation zone in Ukraine.
Russia has a large number of workers from Central Asian nations. But the move requiring military registration and deployment has reportedly led migrants to begin leaving Russia.
The Russian military is said to have lost many soldiers in Ukraine.
The US-based Institute for the Study of War said the legal mechanism that the Russian government is using to recruit and deploy recently naturalized migrants to Ukraine is unclear.
It said the Russian government may be offering naturalized migrants the opportunity to sign a contract for military service or volunteer units in order to avoid deportation or jail time.