International SOS (Isos), the biggest player in the market, said the number of patients it has evacuated to Singapore has been falling since 2006.

That year, its air ambulances ferried more than 1,000 patients here. Two years later, the number was down to 840; last year, it dipped further to around 800.

It could be a blip, but Isos has had 10 per cent annual growth in patients headed to destinations worldwide.

More people have been asking to be moved to Bangkok and Kuala Lumpur in the last three years, said Isos' medical director of operations in Singapore and Malaysia, Dr David Teo.

He was unable to cite figures, but said: "There s a significant increase in the number of patients asking to be taken to Thailand and Malaysia,

instead of Singapore. The most obvious jump is in the number of patients from Indochina opting for Bangkok."

Cost is one reason: Medical costs in Bangkok are 75 per cent that of Singapore's. Kuala Lumpur is even cheaper - at about half what it costs here.

And over the years, the quality of care and medical treatment has gone up elsewhere. Dr Teo said: "In terms of skills, they are all catching up Many of their doctors trained in Britain, the United States or Australia. They ve also built good hospitals like Bumrungrad in Bangkok and Gleneagles Intan and Prince Court Medical Centre in KL."

People in Bangkok and Kuala Lumpur thus no longer need to come here for treatment; Singapore has become an option only for those with deep pockets.

A Mumbai-Singapore trip in an air ambulance, for example, costs between US$80,000 (S$112,400) and US$100,000. This includes getting a doctor from Singapore to fly there to accompany the patient back here.

Dr Teo said a victim of a major car crash who is evacuated here from overseas can expect to pay upwards of $250,000 and even as much as $500,000.

Indonesia remains a major source of patients evacuated here.

Mr Bagus Sayuto, the senior operations coordinator of Global Assistance Healthcare in Indonesia, said his company now carries five to six patients a week, up from three to four five years ago.

Most are tourists, travelling in Indonesia and who suddenly need medical attention. They are covered by travel insurance. The rest are rich Indonesians who already see doctors here, he said.

But Singapore remains the "go-to" place in some niche areas.

For example, the burns centre at the Singapore General Hospital (SGH) is still the only place in the region capable of treating patients with major burns.

Ms Karen Shiu, the operations manager of the hospital's International Medical Service, said it sees five to six such evacuations a year.

Before accepting a foreign burns patient, SGH requires a deposit of between $10,000 and $100,000 depending on the severity of the burns.

Singapore has also so far kept its supremacy in paediatrics, trauma and the care of newborns, including premature babies.

East Shore Hospital took in a pair of premature Vietnamese twins last year, possibly the youngest medical evacuees here.

Born at 29 weeks instead of the usual 38, the twins had practically zero chance of survival had they remained in Vietnam, given that their organs and faculties were not fully developed.

Their accountant father Tran Van Ngu contacted neonatologist Dr Cheng Tai Kin, who flew to Hanoi with two medical teams and brought the 1.3kg twins back here in an air ambulance equipped with an incubator and ventilators.

Dr Cheng, for whom it was the second time he was evacuating premature babies from Vietnam for treatment here, said: "It's not just survival, but the degree of handicap such babies may suffer."

Mr Tran put down a deposit of more than $50,000 for each child; The bill eventually came to $220,000 in all.

The babies, who were discharged on Dec 10 after 80 days at East Shore Hospital, not only survived but are now growing like normal infants their age.