The charity has no direct evidence to link exams with suicide, but found anecdotally that they were a catalyst in increasing stress among students. A spokeswoman said: "We felt strongly that it was something we needed to do - it is vital for them to talk to friends, family or us before it's too late. "
However, the campaign has been criticised by the Associated Examining Board. PR director George Turnbull thought it wrong to associate suicide with exams in the minds of young people.
He said: "I think the Samaritans do a commendable job, but they are rousing the public's fears unnecessarily. It will also cause concern among younger pupils who haven't taken their GCSEs yet."
Figures show that the rate of suicide has increased by more than 34 per cent overall in the past 10 years among 15 to 25 year-olds, and by 71 per cent among young men.
The campaign's message, which will go out on Capital Radio in London and Atlantic 252, is: "Whatever you're going through, we'll go through it with you," and features a 12-year-old boy who shot himself after failing an English exam.
Doug McAvoy, general secretary of the National Union of Teachers, said young people were under increasing pressure to gain higher qualifications because of the lack of job opportunities and competition to carry on to higher education. But he pointed to the way many schools helped exam students by giving them teachers' home numbers for advice once the results were published. "They can tell them it's not the end of all hope, there are other alternatives."