Sites on the internet may be actively encouraging people who are suicidal to kill themselves rather than trying to change their mind, say British researchers.
A worldwide study found people searching the web for information on ways to end their lives were more likely to come across sites egging them on as opposed to offering help.
Almost half of sites contain details on how to commit suicide while one in five hits is for "dedicated suicide sites", Bristol University academics discovered.
The study was carried out in because, the researchers say, although media reporting of suicide and TV portrayals are known to be influential, little is known about the effects of the internet.
It found that "dedicated suicide sites and sites giving factual information about suicide had the highest proportion of number one ranks across searches" with a quarter of the hits providing more detailed information.
The authors also pointed to the dangers from forums and chat rooms.
"Contributors to chat rooms may exert peer pressure to commit suicide, idolise those who have completed suicide, and facilitate suicide pacts," they said and "such discussion may lessen any doubts or fears of people who are uncertain about suicide."
Marjorie Wallace, chief executive of the mental health charity Sane, said: "Sane remains deeply concerned about the possible influence of the internet on suicide rates, not least the ease with which information about particular methods can be found with a simple web search, as this latest study shows.
"We also believe that some websites may further encourage the depressed and vulnerable to attempt suicide through chatrooms and forums, which create virtual communities that can reinforce self-destructive beliefs without encouraging people to seek help.
"The nature of the internet makes it extremely difficult to enforce a ban on pro-suicide websites, but we believe more research is urgently needed to understand why so many are driven to these sites, rather than to content that provides support and advocates prevention."
A spokesman for Britain's Justice Ministry, said: "The law already makes it clear that assisting or attempting to assist suicide is an offence. Actions to assist or attempt to assist suicide could be carried out on or off-line.
The study comes as police continue to investigate another apparent suicide in Bridgend, South Wales where there have been 18 deaths in the area so far over the past year - police insist no evidence of a link between the deaths has been found.
You may like to talk to someone you don't know, who is trained to provide support to people, in confidence. If so, you may consider contacting our helpline, SANEline, on 0845 767 8000. The helpline is open from 6.00pm until 11.00pm every day of the year.
For support outside these hours, Samaritans provide confidential emotional support to anyone experiencing feelings of distress or despair. They can be contacted by phone 24 hours a day on 08457 90 90 90 or email email@example.com.