As many as 650 people in six municipal wards were suffering from diarrhoea caused by an alleged contamination of drinking water and 28 of them were admitted in a city hospital since Saturday night, an official said on Sunday.

Kolkata Municipal Corporation collected samples from different places to detect the cause of the outbreak. "Overall about 650 people reported suffering from symptoms of diarrhoea and affected were from wards 101, 102, 107, 108, 109 and 110. Our Water Supply Department personnel collected samples from water treatment plants from where water is supplied to these areas for testing," a KMC official said.

Mayor Sovan Chatterjee said about 28 people suffering from diarrhoea were admitted to Baghajatin State General Hospital since last night and number of admission has not been increased. The Mayor, who visited the affected wards on Sunday morning, said that around 260-270 people were brought to the Baghajatin hospital.

Dismissing complaints that contamination of drinking water led to the outbreak of the disease in the areas, Chatterjee said: "We have collected samples from 82 places so far to understand the cause of outbreak. It is also found that all in a family drinking the same water were not ill. The problem has been arrested in a greater extent." "We are, however, conducting a complete check of the distribution system," he added.