All the three patients are undergoing treatment at a private hospital here.
Manipur health services director O Ibomcha Singh, while officially confirming the first swine flu case in the state, appealed to the people in the state not to panic as the disease is curable.
The first H1N1 confirmed victim is undergoing treatment at an isolation ward of the hospital. She was admitted to the hospital on February 27 and investigation report of her throat swab tested positive for swine flu later.
The hospital's managing director Kh Palin said the second person showing swine flu-like symptoms was admitted on Friday and her throat swab was sent for laboratory testing on Sunday morning. He added the third patient, an 11-year-old girl, was admitted on Sunday morning.
"The state health authorities have provided all required materials, including medicines and protective gears, for our hospital staff who are dealing with the patients," said Palin.
A few days ago, state health officials had sent the throat swab of a man from Nambol in Bishnupur district, who showed swine flu-like symptoms, for testing to Mumbai.
Though the department is yet to receive the report, the condition of the man, who is staying at his residence in isolation, is better, sources said.
The state government has opened isolation wards at the state-run Jawaharlal Nehru Institute of Medical Sciences and centre-run Regional Institute of Medical Sciences here. Surveillance cells that have been opened in all nine districts of the state are functioning properly.