McDonald's said on Friday that a total of 12 of its branches in Russia had been temporarily closed over the state food safety regulator's allegations of sanitary violations.
The U.S. fast-food chain, which has 440 restaurants in the country, also said that more than 100 inspections were underway at its restaurants in various regions of Russia.
"We are studying the essence of claims in order to determine the necessary actions for the swift reopening of restaurants for visitors," it said in a statement.
Four McDonald's restaurants in Krasnodar were closed on Friday, ITAR-Tass reported, citing the company's press service, while on Thursday the U.S. fast-food giant said that one of its outlets in Serpukhov in the Moscow region had been closed, as well as two restaurants in Sochi.
The watchdog earlier closed three McDonald's restaurants in Moscow, one in Stavropol and one in Yekaterinburg in the Urals region.
The watchdog said it ordered the closures for sanitary reasons, but they coincided with heightened tensions over the Ukraine crisis, in which the United States and European Union have imposed sanctions on Russia and Moscow has hit back by banning a wide range of Western food imports.
McDonald's considers Russia one of its top seven markets outside the United States and Canada, according to its 2013 annual report. Almost 1 million people a day visit its restaurants in Russia.
Material from The Moscow Times is included in this report.