Moscow will begin free mass testing of citizens for the coronavirus from May 15, Moscow Mayor Sergei Sobyanin said on his website on Thursday, with a target of 100,000 people a day by the end of the month.

Around 70,000 blood analysis tests will be offered every few days, in the initial roll-out, Sobyanin said.

Residents will be invited by text message or email to one of 30 Moscow clinics after being selected at random to get their blood drawn for the IFA (immunofluorescence) testing for antibodies.

The results will let the authorities "know for certain how many Muscovites have had the coronavirus and gained immunity, and how many are infected or suspected of having the coronavirus," the mayor said.

Over 130,000 people have tested positive for the coronavirus in Moscow, more than half of Russia's total cases. But Sobyanin said the real spread is "much higher, and our goal is to find the maximum of cases."

Russia as of Thursday had 252,245 confirmed coronavirus infections and 2,305 deaths. That put it behind only the United States in the number of infections, but 18th in the world in total deaths and 58th in deaths per million inhabitants.