Regional prosecutors were conducting a criminal investigation into whether workers committed dereliction of duty or child abuse, the statement said.
It was unclear if charges would be filed against hospital employees.
Earlier this week Russian TV broadcast footage taken with a mobile telephone that showed one sleeping baby lying in a crib with tape on its face.
The Interfax news agency on Tuesday reported that Yekaterinburg city health officials had reprimanded the hospital chief doctor and its chief nurse.
Lack of funding
Russia's health and welfare system fell into disrepair after the break-up of the Soviet Union, with government funding drying up.
Though high world oil prices have filled government coffers recently, many welfare institutions remain neglected. Corruption is common and employees are poorly paid.
In Yuzhno-Sakhalinsk, on the Pacific island of Sakhalin, Tatyana Kutuzova, the regional prosecutor, said that investigators had opened a criminal investigation into whether a worker injected children to calm them down or to help them sleep.
Kutuzova said in comments televised on NTV that the worker lacked the necessary training and qualifications and should not have been working in the kindergarten.