"Our state language center is showing off again. This time they have demanded that I explain why Riga City Council speaks with the inhabitants of Riga on Facebook in the Russian language among others," Usakovs wrote on his Facebook account.
He added that Latvian legislation does not regulate the communications of governmental and non-governmental organizations on foreign social networks.
Usakovs said that he had called on the Latvian Justice Ministry to investigate the "unprofessional" activities of the state language center.
Russians in Latvia make up 26 percent of the country's population, according to national statistics. Some 40 percent of those living in Latvia speak Russian. Latvia's only official language is Latvian.