Among the three, two were Indian nationals who arrived from Thailand at Bangalore airport on Thursday, Jun 18. The other one is a twelve year old boy from United States.
On Wednesday, Jun 17 four persons have tested positive for H1N1 virus in the national capital.
"The four persons who have tested positive for swine flu in the capital are in hospital and undergoing treatment," Dr Shivlal, director of National Institute of Communicable Diseases (NICD), said.
Meanwhile, eight people with suspected swine flu symptoms in New Delhi are still hospitalised as results of the tests carried out on their samples are still awaited.