An advertising campaign using an image of the 7 July London bomb attacks to highlight the problem of young men committing suicide has been criticised.
Calm said the poster was designed to provoke debate
The poster by the Campaign Against Living Miserably uses a picture of the bus explosion in Tavistock Square.
The slogan reads: "Last year, four suicidal British men got our attention. Unfortunately, 983 others didn't."
Bombings survivor Jacqueline Putnam said it was insensitive but Calm said it was to draw attention to the issue.
Ms Putnam, 56, from Huntingdon in Cambridgeshire, said it was wrong to compare the bombers with men who took their own lives for other reasons.
She said the bereaved relatives of the 52 people killed in the attacks were likely to view the bombers as murderers, not men who felt suicidal.
"Calm is a very good cause and nobody is criticising the charity itself because personally I support their aims in trying to help suicidal men," she said.
"But this advert is misguided and insensitive. When those bombers got on those trains they were primarily interested in killing and maiming as many people as possible."
Jane Powell, from Calm, said: "We know that our billboard ads are controversial.
"But it was a conscious decision we made to provoke debate on this issue and draw attention to the tragic fact that, on average, three young men kill themselves every day in the UK.
"The reality is that in the UK the lives of over 1,000 young men a year are passed by without thought or comment. If they died from heroin it would get more attention."
The charity's campaign marks World Mental Health Day on Tuesday and will also feature a separate series of light-hearted radio adverts, including one by comic David Baddiel.