The growing popularity of the Internet could lead to a rise in suicide pacts in which several people kill themselves together, a leading psychiatrist in Britain said on Friday.

Four men in Japan were found dead last month in what police suspect was the latest in a series of such pacts that have claimed dozens of lives in the past two years.

Sundararajan Rajagopal, a psychiatrist at St Thomas’s Hospital in London, fears it could be the first sign of a growing trend because the Web gives people access to others who think along the same lines.

“I don’t know whether the Internet will lead to an increase in the total number of people dying from suicide but it could shift a disproportionate number of people into suicide pacts,” he told Reuters. “The Internet is something that could be a factor in both individual suicides, as well as suicide pacts.”

The pacts in Japan seemed to have been arranged by strangers who planned to kill themselves and met on the Internet via special suicide Web sites. They could be just isolated events in a country which had previously been shown to have the highest rate of suicide pacts, said Rajagopal.

“Alternatively, they might herald a new disturbing trend in suicide pacts, with more such incidents, involving strangers meeting over the Internet, becoming increasingly common,” he added in an editorial in the British Medical Journal.

If that is the case, it could mean that more young people who may have committed suicide on their own, could join other people to take their lives together.

Suicide pacts account for less than one percent of all suicides in England and Wales. Usually they involve people well known to each other who decide to kill themselves together in the same way.

Methods used in suicide pacts tend to be less violent than in single suicides. Poisoning by exhaust fumes from a vehicle is most common. In the United States and England, suicide pacts are most common among spouses. In Japan it tends to be between lovers and in India between friends, according to Rajagopal.

There is also a rare psychiatric disorder called folie a deux, in which two people who share the same delusional beliefs take their own lives. It is more common among sisters who are single.

Alcohol and drug abuse tend to be less common in people who commit suicide pacts than in single suicides.

Rajagopal urged doctors and psychiatrists to be vigilant against the small but not insignificant risk of suicide pacts. “While assessing risk, one may specifically ask whether a depressed patient uses the Internet to obtain information about suicide,” he added in the journal.