Two of the three were on the same flight from New York as Singapore's seventh case, a 30-year- old Australian man who fell ill before he caught the flight. All three patients have been admitted to the Communicable Disease Centre (CDC) 2 at Tan Tock Seng Hospital.

As of Tuesday afternoon, there were eight confirmed patients. The ninth patient, a female student returning home from the United States for the summer holidays, was confirmed that night to be infected with H1N1.

The 19-year-old arrived from New York via Tokyo last Thursday on All Nippon Airways NH901 and developed symptoms on Monday morning.

The other two new patients - a 33-year-old Singaporean woman and an 18-year-old American female visitor - were both on board Singapore Airlines SQ25 from New York via Frankfurt and arrived in Singapore on Monday.

They were seated in rows 19 and 57 respectively. The Australian patient was in row 54.

The 33-year-old Singaporean woman developed symptoms on Monday and was admitted to CDC2 before midnight on Tuesday while the teenager developed symptoms on Tuesday and was admitted yesterday in the early hours. Laboratory results confirmed their infection at 3pm yesterday. Contact tracing for the ninth patient has been done. Two family members have been identified and are currently well. Home quarantine orders will be served on them.

Because the patient developed symptoms more than 24 hours after getting off the plane, the Health Ministry (MOH) has assessed her to be non-infectious during the flight.

For the 10th and 11th cases, passengers who sat in rows 17 to 21, and rows 57 to 59 on flight SQ25 on June 1 who have not been contacted by MOH should call its hotline on 1800-333-9999.