Russia's food safety watchdog has expanded its investigations of McDonald's restaurants to include the semi-autonomous republic of Tatarstan.
The agency carried out sanitary inspections at a number of branches of the US fast-food chain but said it did not plan to shut down the businesses.
The watchdog has closed down three McDonald's restaurants in Moscow, including the iconic eaterie on Pushkin Square, which was the first restaurant opened by the company after the end of the Cold War. The fast-food giant has said the branch is its most popular in the world.
"We are making checks there. There are some irregularities and we are likely to punish them, but we will not close down their restaurants," an agency spokeswoman in Tatarstan said, as quoted by Reuters news agency.
The semi-autonomous region has 17 restaurants that employ around 1,500 staff.
The food safety agency has announced a range of checks at McDonald's restaurants and said it was considering banning certain products as political relations between Russia and the West sank to their lowest point since the end of the Cold War.
Moscow imposed a year-long ban on most food imports from the US, EU, Canada, Norway and Australia after the Western countries imposed tough sanctions against entire sectors of the Russian economy.
The Western measures were imposed over Russia's role in the Ukraine crisis and targeted the banking, defence and energy sectors.