"As of 06.00 a.m. Moscow time (2.00 a.m. GMT), 121 people have been brought to hospitals in Moscow. Another 94 workers have been taken to hospitals near Moscow," the department said, also confirming that two patients remained in a serious condition.
The emergencies ministry said earlier that about 208 people had fallen ill.
The ministry said most of the workers were from Turkey and former Soviet republics, the main source of cheap workforce for numerous construction projects in booming Moscow, many of which are implemented by Turkish firms.
The Federal Service for the Oversight of Consumer Protection and Welfare, which is investigating the incident, said food delivered for the workers was to blame, but added the source of an infection and the infection itself were still to be identified.
"The source of the infection ... and the place where the food was cooked are being clarified," the agency said.
It also said all the patients were suffering similar symptoms: high temperature, nausea, vomiting and diarrhea.
The head of the service, Gennady Onishchenko, said Wednesday the workers could have contracted salmonella poisoning, a potentially lethal infection that affects the gastrointestinal system.
"Most probably, they have contracted salmonella poisoning," he said.
