She was isolated in a room and a 993 ambulance summoned.

'We have all been alerted since Sars, so I knew we had to be prepared as the H1N1 flu can happen to anyone and you never know who will walk in,' he said.

Dr Koh was given a perfect score of 10 out of 10 for his good judgment by both Health Minister Khaw Boon Wan and the head of the Communicable Disease Centre, Associate Professor Leo Yee Sin.

'As far as I am concerned, I did what I needed to. Picking up the case is important as you don't want the person to be undetected and walking around, causing a small community outbreak,' said Dr Koh, who has had his own practice for 17 years.

A Health Ministry spokesman said there were no unprotected close contacts with the patient at the Bedok South clinic.

The doctor was masked and gowned while the clinic staff member who served the patient had only brief contact with her. Other clinic staff members and the sole patient who was there sat more than 2m away.

Speaking to the media at Parliament House, Mr Khaw said: 'Within six hours of her touchdown in Singapore, she was isolated in the hospital. So the risk of her causing a spread in Singapore, I think, should be very low.'

'He could have sent her back or asked her to go to Tan Tock Seng (Hospital) by herself,' he added. Instead, Dr Koh called 993, the dedicated ambulance service for flu victims. At a separate meeting with the media, Prof Leo also commended Dr Koh for assessing the patient's condition appropriately.

Read the full story in Thursday's edition of The Straits Times.