The Sri Lankans, staying in a hotel here, were taken ill after taking breakfast and were admitted to the district hospital, the sources said.
The doctor attending the patients Dr Raman said it is a case of food poisoning.
The condition of three of those admitted and identified as Alava (80), Dasanaike (75) and Chandrakala Surya (33) was serious, he said.
According to the hotel manager, A.K Singh the group of tourists had come here yesterday.
"They had consumed food at some place outside the hotel and were taken ill", he added.