A letter containing an unknown substance was sent to the French embassy in Moscow, the TASS news agency said on Monday, citing law enforcement.
"Employees of the French Embassy received a letter with an unknown substance inside on Monday evening. Law enforcers are currently working at the scene," TASS quoted a source as saying.
The French foreign ministry had no immediate comment on the report.
Earlier in April, Russian media reported that Finland's embassy in Moscow received three suspicious letters, one of which contained an unknown powder.