"It is believed to be a result of rain and problems with the private residential area, that is, lack of sanitation in some of its areas," he said.
He added that heavy rains could cause sewage entering the water.
Read more: Mass poisoning in Izmail: 336 people asked for medical help, more than 200 hospitalized
"The first tests do not give a convincing answer on what kind of poisoning and infection that was," Saakashvili said.
According to him, new victims of poisoning keep arriving, but the situation has stabilized in general. Chief sanitary doctor of Ukraine has departed to Izmail, he said.
Read more: About 250 poisoned Izmail residents (147 children among them) asked for medical help - Epidemiological Service
336 people asked for medical help in Izmail as of 7 a.m.
Mayor Andrii Abramchenko reported that state of emergency was introduced in the city. On Saturday, the emergency workers went door-to-door in the private area, allowing time to identify a certain number of those in need of help.
The police opened a criminal proceeding due to the outbreak of intestinal infection.