A new study - the most detailed yet into the phenomenon - concludes it is now claiming the lives of people who would never before have gone through with an attempt to commit suicide.

The study by a group of Hong Kong academics, published in the British Journal of Psychiatry, found she was the first person in the world recorded as taking her life by this method. Even the notorious 1993 Japanese suicide manual written by Wataru Tsurumi makes no mention of charcoal-burning.

Today, one in four people who kill themselves in Hong Kong do so by charcoal-burning, the second most common method after jumping from high buildings.

Elsewhere, in countries and territories around the region where the method has never before been recorded, people are killing themselves by charcoal-burning in increasing numbers.

The method is already firmly established in Japan, where it is claiming the lives of scores of people, including three people in their 20s found dead in a car parked near a shrine 150km north of Tokyo after closing the windows and doors and burning charcoal inside.

The rapid spread of what is seen as an 'easy' way to take your life last week brought together suicide prevention experts from Japan, Taiwan and New Zealand in Hong Kong to discuss ways of tackling the phenomenon.

Dr Paul Yip Siu-fai, director of the University of Hong Kong's Suicide Research and Prevention Centre and one of the authors of the British Journal of Psychiatry report, said of the charcoal-burning trend: 'It is really something made in Hong Kong.

'We have seen cases in southern China, in Shenzhen. We have seen cases in Japan. Since 2000, they have had more and more people dying of charcoal burning and they have never seen that before. It has only happened since the case in Hong Kong.'

Dr Yip, along with a team of Chinese University psychiatry experts, studied the cases of 160 Hong Kong people who have died after burning charcoal and interviewed 25 people who survived committed attempts to commit suicide by charcoal-burning.

What they found, according to Professor Dominic Lee Tak-shing, is that people who commit suicide by charcoal-burning are more likely to be economically active, 25 to 54-year-olds, living in private housing, and less likely to be suffering from mental illness or disability.

Significantly, they are three times more likely than people who commit suicide by other methods to be suffering from bad debts and financial difficulties - and researchers also believe from interviews with survivors that if it was not for the availability of charcoal-burning as a method, they would probably not have gone through with their attempts.

'That is the most saddening and shocking thing,' Professor Lee said. 'When you talk about suicide, if you look at the general profile of people who commit suicide, it is people who are old, unemployed and not economically active.

'But if you look at charcoal-burning suicide victims, they are economically productive. They are working. They have no mental illness. They are like everyone on the street but they are not very smart at looking after their money.

'When the economic climate shifted, the balance tilted and they ran a downhill course until the whole thing got out of hand. It is a great loss to society because, had these people not killed themselves, they would have continued to contribute to the prosperity of Hong Kong.'

The Sheung Shui suicide that started the trend in 1998 dovetailed with an economic downturn and spiralling debt, fuelled by the easy availability of credit. Many of the survivors of suicide attempts interviewed by the academics were unaware of the high interest rates they were being charged for credit cards.

'Many applied for additional cards to cover their growing debt,' the report found. 'At that time it was easy for people to be granted a number of credit cards from different banks and lenders. Our informants in this study each had an average of four credit cards.'

The most extreme case the researchers found was one man with 15 credit cards and a credit limit of $400,000, 33 times his monthly income. 'Suicidal thoughts eventually turned into action, often precipitated by relentless harassment from the debt collectors,' the report said.

Dr Yip warned: 'The problem isn't just in Hong Kong. In mainland China they are encouraging more and more people to take out bank cards and I think the problem there might become even bigger because they have less experience in managing these cards.

'Chinese people always like to spend a bit more. They like gambling. In China, there are 1.2 billion people and if 10 per cent of them use credit cards it could become a huge problem.'

In Hong Kong in 1997, 10 per cent of suicides related to financial problems. Five years later, that figure had climbed to 40 per cent. Over the same period the number of suicides in Hong Kong climbed by 50 per cent to just under 1,300 in 2003 - 26 per cent of those by charcoal-burning. Would those 26 per cent of cases still be alive if charcoal-burning was not available as a method?

'Some people we interviewed were extremely determined,' Professor Lee said. 'For this small proportion of people, if there were no charcoal burning they would have used other methods.

'But the substantial number of the people we interviewed chose the method because it is perceived as painless and comfortable and non-disfiguring. Without charcoal-burning they would have thought twice before attempting to kill themselves.

'The other common methods of suicide are jumping from heights and hanging. Both of those are very violent and uncomfortable and it takes a lot of courage to do either of them.

'Imagine going to the top of a high building and looking down before jumping. It's painful and very disfiguring and people don't like to have their bodies in pieces and in a mess when they go. Charcoal-burning is perceived as an easy solution because they believe they can die without pain.'

The reporting of charcoal-burning suicides in mass-circulation Chinese language newspapers is blamed by the researchers for popularising the method from the first case in November 1998 onwards.

The way cases have been covered since reinforces the perceptions.

Their study says the newspaper reports 'conveyed an implicit message that charcoal-burning is an easy, painless and effective means of ending one's life, especially in the face of business failure or insurmountable debts'.

Testimony from survivors tells a different story.

'It is a suffocating experience which is extremely unpleasant,' Professor Lee said. 'The process involves displacing oxygen, almost like being strangled, and people who survive say it is not something they had anticipated or thought carefully about.'

The academics agree that the easiest way to help reduce the death toll from charcoal-burning is by making charcoal less easy to buy.

They want to see supermarkets restrict the sale of charcoal to shops near barbecue areas and stop selling it in urban areas where few people have balconies or roof tops to hold barbecues.

By reducing the accessibility, they argue, you create a window of opportunity in which the person intending to kill themselves can be helped.

They also believe supermarkets and shops should tell staff to be on the look-out for people who appear depressed and act strangely when buying charcoal and to use their discretion to refuse to sell it to people who might be at risk.

Measures such as mandatory locking of gun cabinets in the United States and restrictions on the sale of paracetamol in Britain have helped bring down suicide rates in those countries.

The researchers believe restrictions on charcoal sales in Hong Kong might have a similar effect.

Dr Yip said suicide researchers had to combat myth and prejudice.

'The myth is that suicide is not preventable, and that it doesn't matter what you do, the people involved will find a way to kill themselves,' he said. 'That is not true. Then there is prejudice against people who are suffering from depression and mental illness.'

Professor Lee said: 'If these charcoal-burning suicides happened in America I would imagine there would be a class action by victims' families to sue [stores] for making charcoal available unnecessarily, or they would be sued for failing to spot that the person buying the charcoal was so depressed.

'If it happened in England, there would be an activist group who would lobby the politicians to do something. But in Hong Kong we don't have those class actions or activists.

'Our failure to act on this issue is really a reflection on Hong Kong society.'