'A short while ago, it was reported that seven shopping centres in Moscow had received such calls. Now this figure has grown, but the specific number is still unknown', the source said.
The source stressed that the buildings had been cordoned off and inspections were being conducted with the help of sniffer dogs.
The phone calls that prompted the evacuation of several Moscow shopping malls were received from abroad, according to the Russian Emergency Services.
'Anonymous calls are from outside of Russia. It is currently being established where exactly they come from', an emergency services spokesperson said, adding that some 4,500 people were evacuated from the shopping centres and Moscow Kiyevsky railway station.
A spokesperson of the Russian Interior Ministry's Moscow head office told Sputnik later on Wednesday that all bomb threat calls were fake.
'After examining the information received, no dangerous devices were found', the spokesperson said.
The statement has been made after a series of anonymous phone calls with claims that explosive devices were planted in various buildings started in Russia in mid-September 2017. According to Sputnik's source in the emergency services, nearly 2.5 million people in 180 Russian cities have been evacuated since then.
Over 3,500 buildings have been allegedly targeted during this period, but the threats were never confirmed.