Singapore confirmed three more Influenza A/H1N1 cases on Thursday, bringing the total cases here to four, the country's Health Ministry said.

The ministry said in a statement that the country's second confirmed case is a 43-year-old female Singapore permanent resident who returned to Singapore from San Francisco via Manila on Tuesday at 17:50 local time. She was on Singapore Airlines, SQ 917 and was seated at 33H. She became unwell while on board.

The third confirmed case is a 28-year-old American female who is working in Singapore. She returned to Singapore from Honolulu via Tokyo on Tuesday at 23:53 local time, on United Airlines, UA 803. She was seated at 33C. She became unwell on Tuesday.

The fourth confirmed case is a 28-year-old Singaporean male who returned to Singapore from Chicago via Hong Kong on Monday at 00:36 local time. He was on United Airlines, UA 895 and was seated at55H. He became unwell on Monday.

The ministry said that the patients are currently being treated at the Communicable Disease Center at the Tan Tock Seng Hospital. Their symptoms are relatively mild and all of them are in stable condition.

The ministry said that contact tracing of their close contacts, including passengers on the same flights, is ongoing. They will be quarantined and provided with antiviral prophylaxis.

Singapore confirmed on Wednesday the first case of Influenza A/H1N1, a 22-year-old Singaporean woman who returned from New York on Tuesday.

(Xinhua News Agency May 29, 2009)