Samaritans' outgoing chief executive, Simon Armson, has admitted a problem exists and is looking at hiring consultants to recommend how to improve staff relations.
"I am aware of difficulties and concerns people are having at the moment, and although I can't comment on any specific case, it's important to say that the charity doesn't condone bullying or harassment in any shape or form," he said.
As the charity celebrates its 50th anniversary this week, head office staff have accused the Samaritans of hypocrisy over its plans to launch training programmes to help businesses boost morale.
"A number of us feel so demoralised and let down by the organisation on a number of levels," said one full-time employee, who declined to be named. "We're at the point where we're practically calling our own support line."
Another source claimed that the organisation is so focused on its volunteers that general office employees are made to feel peripheral and denied the appropriate training and support needed to cope with the emotionally demanding nature of their jobs.
"The level of stress that we're under is almost intolerable," he said.
"Grievances fall on deaf ears, and although we've put up a tremendous struggle against fear and intimidation, when we've voiced our concerns, senior management and trustees were either unsupportive or intimidating."
In one case this year, a group of full-time staff lodged a formal complaint against a senior manager, alleging bullying and harassment. The grievance was not heard for 11 weeks, and staff members were never officially informed of the outcome.
"I would say 80 per cent of full-time staff are ready to walk out and it is only their commitment to the people we help that is stopping more doing so," said the employee.
But Armson said the allegations must be put in context to the size, scope and level of service that the charity provides. "I am in no way undermining anyone's feelings, but we have 70 staff and 18,500 volunteers, who all work to deliver a highly valuable service," he said. "That service needs to go on and our credibility needs to remain intact. We all have to work together to sort through any problems we might have."
In the summer, staff approached Amicus about getting union representation.
Union officer Tina McKay said she hoped to reach an agreement with management on representation by the new year.